—AN INVITING GENUS FOR THE STUDY OF HEREDITY W. E. SAFFORD Bureau of Industry, U. S. Department of Agriculture HE GENUS Datura belongs to sit peregrinae, vocabulum persistere the , a botanical family valet, cum a latina derivari potest; Tremarkable for the narcotic proper- dantur et daturae forte in Indiis posthac ties of many of its members. Perhaps semina a lascivis foeminis maritis the most celebrated of them all is the inertibus."1 mandrake (Mandragora officinalis) so Fig. 10 is reproduced from a photo- frequently mentioned by Shakespeare, graph of East Indian metel nuts in which during the Middle Ages was the drug collection of the United States used in amorous incantations and was National Museum. Fig. 11 is a reduced believed to have magical virtues. reproduction of Fuchsius's illustration According to early herbalists it would referred to above. In this figure the shriek aloud when torn from the corolla is represented as 6-toothed, but ground, causing deafness and even normally it is 5-toothed. death to him who dared gather it. To escape the penalty, a dog was used SEVERAL VARIETIES DESCRIBED by the herbalist to wrest it from the In establishing the specific name ground, the earth having first been in the first edition of his carefully removed from about it and Species Plantarum (p. 179. 1753),- the dog tied to the stalk. An early Linnaeus definitely states: "Habitat illustration represents the dog writhing in , ," and cites his previous in the agonies of death after having description of it in Hortus Cliffortianus accomplished the feat. Other famous (p. 55. 1737). Here it is called Datura narcotics of the Solanaceae pericarpiis nutantibus globosis, and is are the deadly nightshade (Atropa identified with the Arabic metel-nut belladonna), henbane (Hyoscyamus and the East Indian dhatura, or dutra, niger) and the dutra or dhatura (Datura "by many called Stramonia." Several metel) of the Hindoos. distinct formsorvarieties are described; The last named plant derives its among them, a, with a double white specific name from the jous-methel, corolla (flore albo pleno); /3, with a or "metel nut," of the Arabic pharma- simple white corolla (flore violaceo copaea, described by in the simplici); y, with a double or triple eleventh century together with nux- violet corolla (flore violaceo duplici myristica, or nutmeg, and nux-vomica, triplicive): 6, with a double corolla or strychnine. From Dioscorides' white within and violet without (flore translation of Avicenna's description, pleno, intus albo, foris violaceo). In the this so-called nut was recognized by accompanying illustrations (Fig. 12) Matthioli and other early botanists as are shown the typical form of Datura the fruit of a solanaceous plant, which metel L. with simple white corolla was figured in 1542 by Fuchsius under (No. 1) together with its dried fruits, the name "Stramonia, or Rauchaep- "pericarpiis nutantibus globosis" (No. ffelkraut." In establishing the genus 2), and its varieties "Flore albo pleno" Datura two centuries later, Linnaeus (No. 3) and "flore pleno, intus albo, formed a generic name from the East foris violaceo" (No. 4), the two last Indian Dutra, or Dhatura, giving it a named photographed from Latin form, and explaining it by the propagated at Arlington by Mr. H. A. following pun: "Daturae, licet originis Allard of the Bureau of Plant Industry. 1 Linnaeus. Hort. Cliffort, 56. 1737. 178

Downloaded from https://academic.oup.com/jhered/article-abstract/12/4/178/785129 by University of California, Santa Barbara user on 26 March 2018 THE ARABIAN JOUZ-METHEL, OR METEL NUT Described by Avicemna in the eleventh century (Datura metel L.). These are specimens from the drug collection of the U. S. National Museum. Datura is a genus of large, coarse, rank- smelling, poisonous plants of the nightshade family, growing in waste places, with large, showy, funnel-shaped flowers succeeded by globular, prickly, four-celled capsules. All the species, of which the thorn-apple or Jimson weed is the best known, possess narcotic and poisonous prop- erties. (Fig. 10.) There can be no question as to the described its use by the woman of Goa identity of Linnaeus's Datura metel, as follows: "They have likewise an and there can be no excuse for calling hearbe called Deutroa which beareth a it Datura alba or Datura fastuosa (the seed, whereof bruising out the sap they latter name applied to its forms with put it into a cup or other vessel and double corollas) nor for transferring its give it to their husbands, eyther in perfectly valid name to the American meate or drinke and presently there- "downy thorn-apple" (Datura innoxia) with the man is as though hee were described by Miller in 1768.2 halfe out of his wits and without feeling, Both the white-flowered and the or else drunke (doing nothing but) colored varieties of Datura metel axe laugh, and sometimes it taketh him used as intoxicants; it would be inter- sleeping (whereby he lyeth) like a dead esting to determine which is the most man, so that in his presence they may efficacious. In 1563 Garcia de Orta, doe what they will and take their physician in charge of the hospital of pleasure with their friends, and the Goa, Portuguese India, published an husband never know it. In which sort account of the criminal uses of dhatura he continueth foure and twentie hours by servants and highway robbers. long; but if they wash his feete with Thirty-three years later Huyghen van cold water hee presently reviveth and Linschoten, in the journal of his travels, knoweth nothing thereof but thinketh 2 For the synonomy of these two species see the author's Synopsis of the Genus Datura, in Journ. Wash. Acad. Sci. 11:—1921.

Downloaded from https://academic.oup.com/jhered/article-abstract/12/4/178/785129 by University of California, Santa Barbara user on 26 March 2018 A SIXTEENTH CENTURY ILLUSTRATION OF DATURA This is a reduced reproduction of Fuchsius's illustration figured in 1542 under the name "Stramonia," or Rauchaepffelkraut (Datura metel L). It was recognized by the botanists of that time as a solanaceous plant, but the genus Datura was established two centuries later by Linnaeus. (Fig. 11.).

Downloaded from https://academic.oup.com/jhered/article-abstract/12/4/178/785129 by University of California, Santa Barbara user on 26 March 2018 VARIETIES OF DATURA METEL L No. 1 is a typical, white-flowered single form often called D. alba, and No. 2 shows specimens of its dried fruit commonly used as a narcotic. No. 3 shows the form having double white corollas, usually called D. Jastuosa; and No. 4 is the form with a double purple corolla. Both the white flowered and the colored varieties of Datura metel are used as intoxicants. (Fig. 12.)

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he had slept." . . "This hearbe," he efficacious; but this I have not seen adds, "groweth in all places in abun- nor tried, having other medicines more dance, and although it is forbidden to safe for the purpose."3 be gathered or once used, never-the-less The high esteem with which this those that are the principal forbidders plant was regarded by the ancient of it are such as dayly eat thereof." Chinese is indicated by Li Shi-Chen, Christoval Acosta, in his Tractado in his celebrated work on the Materia de las Drogas y Medicinas de las Indias Medica of China, Pen ts'ao kang mu, Orientales (1578) likens the trumpet- published in 1590. According to this shaped flowers of this plant to those of author the Chinese name of this plant, a Convolvulus and its seeds to lentils. man t'o lo hua (probably derived from "Among the Hindu enamoradas," he the Sanscrit) is taken from a famous says, "few are without Datura seeds Buddhist sutra, "Fa hua ching," in among their most highly prized treas- which it is stated that when Buddha ures." They were ground to a powder preaches a sermon the heavens bedew and administered in wine or some other the petals of this plant with rain-drops; medium as a love potion to the object and according to a more ancient of their affection; and, Acosta adds, tradition of the Taoists, the name "he who partakes of it is deprived of his of the plant is that of one of the circum- reason (queda enagenado) for a long time polar stars, and every envoy sent down laughing, or weeping, or sleeping, with from this star to the earth is supposed various effects, and often times talking to carry in his hand one of its flowers; and replying, so that at times he so that one of the Chinese came to call appears to be in his right mind, but the flower by the name of the star. really being out of it, and not knowing Li Shi-Chen gives a pretty good the person to whom he is speaking, nor description of the plant, which he says remembering what has happened after has resembling those of an egg- his alienation has passed. Many plant, flowers with a white hexagonal mundane ladies are such mistresses corolla, blooming in the eighth month and adepts in the use of this seed, that (September) and round prickly fruits; they give it in doses corresponding to but his description is corrected by a as many hours as they wish their poor Japanese botanist, Ono Ranzan, who victim to be unconscious or trans- says that the flower is normally penta- ported. And truly if I were to tell gonal instead of hexagonal, and this stories of what I have heard or seen correction is sustained by Siinuma relating to this matter, and the different Yokusai, another authority on old ways I have seen people act when under Japanese botany, who gives a very good the influence of the drug, I would cover illustration of the flower in question many sheets of paper; but as this is not (Fig. 12, No. 1) identifying it with the necessary I will refrain. I will only typical white-flowered form of Datura say that I have never seen any one die metel, which is known to the Japanese from its effects; and I have seen some by the name Chosen-asagao, or "Korean who have gone about for several days Morning-glory."4 perturbed, and this must have been because it had been given to them in A synopsis of the genus Datura was too large doses, which if too great will published by the writer in the Journal cause death because this seed contains of the Washington Academy of Sciences venomous parts, although the Gentiles in order to clear up the existing con- administer it as a diuretic with pepper fusion in its treatment by taxonomists and betel leaves and say that it is and to straighten out conflicting state- ments as to the origin of some of the 'Acosta, Christoval. Tractado de las Drogas y medicinas de las Indias Orientales, p. 88. 1578. 4 It is interesting to note in this place that Datura stramonium, our common Jamestown weed, which many botanists have supposed to be of Asiatic origin is called in Japan yoshu Chosen-asagao, yoshu, signifying "foreign."

Downloaded from https://academic.oup.com/jhered/article-abstract/12/4/178/785129 by University of California, Santa Barbara user on 26 March 2018 VARIETIES OF DATURA STRAMONIUM L. No. 1 shows the leaves and fruit of the purple flowered form with armed capsules, usually called D. tatula; No. 2, leaves and fruit of the green-stemmed, white-flowered form with armed capsules, the typical form of the species; No. 3, purple flowered forms with armed and unarmed capsules; and No. 4, the white-flowered form with unarmed capsules, Datura inermis Jacq. These forms are admirably adapted as material for the study of heredity and mutations as they readily lend themselves to experiments in cross-pollination. In one of the recent press dispatches sent by the leader of the Mount Everest Expedition, there was this description: "By the roadside were most marvelous hedges of daturas, 15 to 20 feet high, and covered with hundreds of enormous white trumpet-shaped blooms, each eight inches in diameter and fully 12 inches in length. At night they seem to gleam with a kind of phos- phorescence emitting a strangely sweet scent." (Fig. 13.)

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most common species.5 An account photographed by the writer. The most of the ceremonial and medicinal uses abundant, with reddish-purple stems, of the various species in both the Old lavender-colored corollas, dark violet and the New World will appear in the anthers, and upright, prickly capsules, forthcoming Annual Report of the was identical in appearance with the Smithsonian Institution. form commonly called Datura tatula. In recent years certain varieties of Next in abundance, occurring in about the Jamestown weed (Datura stramon- equal numbers, were white-flowered ium) have been used in the study of the plants with prickly capsules like phenomena of heredity and mutations. the typical Datura stramonium and All of the species are admirably lavender-colored plants with smooth, adapted for experiments in cross- or unarmed, capsules; and least abun- pollination. The anthers of the flower dant of all was a form with white chosen for the female parent can be flowers and unarmed capsules, identical removed easily before their dehiscence in all respects with Datura inermis. In and the flower covered before the Figure 13, No. 1 shows armed capsules of corolla unfolds. Pollen can be obtained the purple-flowered form commonly with equal facility from the covered or called Datura tatula: No. 2, pods of the unfolded flower chosen as the male typical white-flowered D. stramonium; parent and applied to the stigma of No. 3, armed and unarmed pods of the emasculated flower. By this simple of purple-stemmed, lavender-flowered method white-flowered and purple plants; and No. 4 the green-stemmed, forms, and forms with prickly and white-flowered form with unarmed with smooth capsules can readily be capsules usually called Datura inermis. crossed. Results of experiments of The evidence offered by the relative this nature made by Miss E. R. abundance of the various forms here Saunders confirmed in a most striking shown corroborates the results of the manner the conclusions arrived at by experiments of Miss E. R. Saunders Mendel relating to inheritance.6 already referred to. Of the antagonis- tic color characters the violet was In the summer of 1916 the writer dominant and the white-flowered form collected specimens of purple flowered recessive, and of the contrasted Datura stramonium growing at Round forms the prickly one was dominant Hill, Virginia, some of which bore and the unarmed recessive.7 Very unarmed as well as prickly pods upon similar results were presented in March the same plant. A comparison of the 1917, by Blakeslee and Avery in the former with specimens of the so-called form of a living diagram showing the Datura inermis showed them to be average results of a dihybrid cross identical, while the prickley pods were between the purple-flowered, purple- like those of the purple-flowered Datura stemmed Datura stramonium tatula tatula and the white-flowered Datura armala (PAr) and the white-flowered, stramonium. green-stemmed Datura stramonium In July 1916, seeds bearing the label inermis (Win). In the latter case all "Datura inermis," received from F. A. the first generation hybrids had purple Miller of the Eli Lilly Company, flowers and prickly pods, while in the Indianapolis, were planted in the drug second generation there were 9 purple garden at Arlington by Dr. Stockberger armed, 3 white armed, and 3 purple of the Bureau of Plant Industry. unarmed, and 1 white unarmed, in Plants of four distinct forms were the perfect conformity with Mendel's law.8 result, all of which were collected and

sSafford, W.E., Synopsis of the Genus Datura. Journ. Wash.Acad. 11: 173-189, 1921. 6 See Bateson, W., and Saunders, E. R., Experimental Studies in the Physiology of Heredity; in Reports of the Evolution Committee of the Royal Society of London 1:21, 1902. 7 See Bateson, W., and Saunders, E. R., Experimental Studies in the Physiology of Heredity, in Reports of the Evolution Committee of the Royal Society 01 London 1:21. 1902. 8 Blakeslee and Avery, Adzuki Beans and Jimson Weeds, in Journ. Hered. 8:125-131. 1917.

Downloaded from https://academic.oup.com/jhered/article-abstract/12/4/178/785129 by University of California, Santa Barbara user on 26 March 2018 AN AMERICAN SPECIES, DATURA METELOIDES DUNAL No. 1 shows a flower and fruit of this species, which occurs in two distinct color forms, one with white and the other with pale blue or lilac-colored corollas. No. 2 is a blue tinted flower grown at Arlington, Virginia. No. 3 shows some fruits of the blue and white flowered forms collected at Sacaton, Arizona; and No. 4 some immature fruits of the blue-tinted form grown at Arlington, showing expanded persistent bases of the calyces. (Fig. 14.)

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In making their experiments Blakeslee America. The latter, which as already and Avery encountered numerous muta- stated, is the dominant form is natur- tions, chiefly in the relative length of ally most common. De Candolle the notes of the stem, and in the form regretted the absence of vernacular of the leaves and capsules. Among the names for them, which he recognized results of their observations was the as important in indicating whether discovery that the mutations were they were endemic or imported. For- sudden, though of rare occurrence, and tunately we have vernacular names for that they transmitted their characters the very species in question. The —chiefly through the female sex— Aztec name tlapatl still survives in to only a part of their offspring. Mexico and is applied to both the That the purple and white-flowered white-flowered and purple-flowered forms of Datura stramonium used in forms, sometimes modified to the forms these experiments are specifically iden- tlapd or tapatl. Professor Pittier re- tical is certain. The statement has cords it from Salvador under the been repeatedly made that there is a form tapd. There is no possibility difference in the relative length of the that these names are of European prickles arming the capsules of the two origin, introduced by the Creoles. color forms, but in specimens collected In addition to them there are Creole by the writer no such difference could names, it is true, such as the significant be detected. De Candolle in discussing "vuelve-te-loco" in Guatemala. That the possibility of the separate origin of the recessive white-flowered form the two color-forms makes the follow- should be "naturalized . . . probably ing remarkable suggestion: "Si ces deux from Asia" and the dominant purple- formes sont deux especes, il est tres pos- flowered form, so closely allied to it as sible que l'une fut de l'ancien et l'autre to be indistinguishable except by the du nouveau monde, et alors je croirais color of its stem and flowers, should be le Tatula americain plutot que l'autre." "naturalized from tropical America" (If these two forms are two species, it is unthinkable; and there is no valid is very possible that the one was of the reason for questioning Linnaeus, who, Old World, and the other of the New, in establishing the species Datura and then I should believe the Tatula stramonium, adds to his brief descrip- is American^rather than the other) tion: "Habitat in America, nunc vul- After -expressing his surprise that garis per Europam." Humboldt and Bonpland had found Datura stramonium played an im- Datura tatula to be common in the portant part in the religious rituals of mountains of Caracas, he still clings to certain aboriginal tribes of Eastern the possibility of its Old World origin, North America, who used it in the saying: "On indique peu de noms ceremonial called huskanawing, in vulgaires pour ces Datura, et le plus which boys arriving at the age of souvent ceux usites par les Creoles sont puberty were initiated into the status derives des langues europeens et trahis- 10 9 of manhood. It takes its common sent une importation." ("Only a name Jamestown Weed (now modified few native names for Datura are to "jimson weed") from its effect upon given, and those most frequently used soldiers sent in 1676 to Jamestown to by the Creoles are derived from Euro- quell the uprising known as Bacon's pean languages and betray their im- Rebellion. The behavior of the soldiers portation.") As a matter of fact both while under its influence, as described the white-flowered Datura stramonium by Beverley, recalls the intoxicating and the purple-flowered D. tatula are effects of the Asiatic Datura metel found growing spontaneously in many mentioned by the writers already parts of North, Central, and South cited.11 9 De Candolle, Alphonse. G£ographie Botanique, 2:773. 1855. 10 Beverley, Hist. Virginia book 3:32, 39. 1705. 11 Beverley, Hist. Virginia book 2:24. 1705. Safford, in Annual Report Smithsonian Institu- tion for 1916:408. 1917.

Downloaded from https://academic.oup.com/jhered/article-abstract/12/4/178/785129 by University of California, Santa Barbara user on 26 March 2018 FLOWERS OF TREE-DATURAS OF No. 4 is the Datura arkorea L. variety with remotely toothed leaves and fiowers larger than the type collected in the Peruvian Andes; No. 3, Datura suaveolens H. & B. with inflated calyx, toothed at tip, and coherent anthers, photographed from a cultivated specimen; No. 2, Datura sanguinea R. & P. with glabrous orange and scarlet flowers and narrow, entire leaves; No. 1, D. Rosei Safford with pubescent saffron-colored flowers and sinuate velvety leaves. (Fig. 15.)

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Thus.far experiments in cross-breed- to that of a Convolvulus and its seeds ing Daturas have been confined to to lentils. forms of Datura stramonium. Other All the Daturas thus far described species of this genus occur in marked produce an abundance of seeds. Few color forms. They vary in the arma- of the tree-daturas, or Brugmansias ture of their fruits and are equally of South America, on the other hand, inviting for study, especially the Asiatic are known to be fertile in cultivation. Datura metel above described. The They therefore present greater diffi- latter has still another interesting culties as material for the study of form-variation: its corollas as already heredity. It is quite possible that in stated, are sometimes simple and their native habitats they are pollinated sometimes double. Simple and double by long-billed humming birds, and flowers of the purple-flowered form, those that bloom in the evening and usually calledD.fastuosa, were collected are fragrant during the night may like by the writer from a single plant in the other Solanaceae, attract nocturnal garden of Mrs. Augustus Saint Gau- moths allied to the Sphingidae with dens, at Coconut Grove, Florida. proboscids long enough to reach the Simple and double flowers are also nectar at the base of the filaments. encountered in other sections of the Lagerheim noticed that certain species genus, including the Brugmansias or growing in Ecuador are cross-polli- tree-daturas of South America. nated by a humming-bird belonging Datura meteloides, an American spe- to the genus Docimastes having a bill cies used ceremonially by the Mexicans, 12 cm. long. This bird visits the long Zufiis, and California Indians, occurs in pendulous blossoms apparently in quest two marked color forms, one with white of small insects as well as of nectar. and the other with pale blue or lilac- Shorter-billed species rupture the cor- colored corollas. In Figure 14 these olla tubes from without. The flowers forms are shown together with their of the tree-daturas vary greatly in color characteristic nodding pods subtended as well as in the form of the calyx. The by an expansion of the persistent base latter in some species is spathe-like and of the circumscissile calyx. Very closely pointed, in others notched or toothed allied to this species is the "Downy at the apex. It would be of 'great Thorn-Apple" {Datura innoxia Miller) interest to cross-pollinate the white- aJready referred to, an American plant flowered Datura arborea with the re- often confused with D. metel L., cently described red-flowered D. rubella but differing from that species in its which closely resembles it in form; and downy indument and its 10-toothed the orange-flowered D. aurea or the instead of 5-toothed corolla.12 Another delicate pink D. mollis with the white- form closely related to D. meteloides flowered D. Candida. Crosses 1 light and still more closely to D. innoxia, is also be made between the Brazilian D. discolor, also with nodding fruit D. suaveolens, which has coherent and a 10-toothed corolla, but easily anthers, a 5-toothed inflated calyx and distinguished from both of its allies slender fusiform fruit with other species by its black seeds. The narcotic plant having distinct anthers, spathe-like called Ololiuhqui by the Aztecs was acuminate calyces, and spheroid or oval undoubtedly a Datura of this section, fruits. It would be equally interesting although it has been erroneously de- to observe the effects of crossing Datura scribed as a species of Convolvulus, sanguinea or D. rosei, species with the or Ipomoea. Hernandez, in describing fruit enveloped in a persistent husk-like it, uses nearly the same expressions as calyx, with other species like D. pittieri, Acosta when he speaks of Datura metel, in which the calyx is quite deciduous. comparing its trumpet-shaped flower Figure 15 shows the flowers of four 12 Typical specimens of Datura innoxia Miller, called by the Aztecs Nacazcul, or Toloatzin, were collected by Dr. Edward Palmer in 1898 in the vicinity of San Luis Potosi, Mexico (No. 677).

Downloaded from https://academic.oup.com/jhered/article-abstract/12/4/178/785129 by University of California, Santa Barbara user on 26 March 2018 FRUITS OF TREE-DATURAS OF SOUTH AMERICA No. 4, typical form of D. arborea L., with entire leaves, and spheroid fruit; No. 3, the Datura arborea L. variety with larger flowers and leaves remotely toothed instead of entire; No. 2 D. pittieri Safiord, a fruit quite devoid of vestiges of the calyx; No. 1, D. sanguined R. & P. a fruit enveloped in persistent husk-like calyx. (Fig. 16.)

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contrasted species of the section Brug- rosei a closely allied species with sinuate mansia, or tree daturas: Datura arborea, or lobed velvet leaves, and pubescent D. suaveolens, D. sanguinea, and D. saffron-colored flowers with tomentose rosei. Figure 16 shows fruits of plants peduncles. belonging to the same section: No, 1 of the typical form of D. arborea, with Tree daturas are usually propagated entire leaves collected by Mr. 0. F. by means of cuttings. It is quite Cook in the Andes of Peru; No. 2, of possible, however, to obtain seeds of a second form of the same species with most of them in their natural habitats, remotely toothed leaves and somewhat and by crossing their progeny developed larger flowers; No. 3, of Datura san- varieties rivaling the hybrid Cannas, guinea with narrow entire leaves and Begonias and other beautiful creations glabrous red flowers; and No. 4, of D. of recent years. EDUCATION AND THE SIZE OF FAMILIES Worcester, Mass. interesting data on this subject in an The Editor, article about the families of scientific JOURNAL OF HEREDITY, men. This data is especially valuable Washington, D.C. as it was collected without any refer- Dear Sir: ence to the theory that I am support- There have been a number of ing. He shows that while early investigations as to the size of families marriages, in general, produce larger of college graduates, compared to families, in the case of scientific men nongraduates, the universal conclusion those who marry between the ages of being that the college graduates do not 25 and 30 have the largest families. He produce enough children to maintain further shows that the educated wife their numbers. Further figures show of a scientific man has nearly if not that the graduates of women's colleges quite as large a family as the un- produce but little more than half as educated wife. many children as those from co- These two facts have received but educational colleges, largely because a little consideration, but are extremely smaller proportion of the former marry. significant. Further investigation These facts are well enough established should be undertaken in other groups so that it is not necessary to quote of society along similar lines, such as figures, but the interpretation of these among the doctors, ministers, laborers, figures is a subject that badly needs etc. It would also be interesting to see study. if the same results are to be found Some investigators look at the small among the unsuccessful scientific men, number of children in the families of for Cattell only considered the success- the women graduates, and jump to the ful ones. Possibly the relationship of conclusion that they have located the early marriage and large families is not trouble, but the records of women in one of cause and effect, but is only a the same class of society, who do not common characteristic of the same attend college, show a similar condi- classes in society, and that if we could tion. There may be a fault here—there postpone the marriage of the feeble very likely is—but for the principal minded they would have even larger causes we must look further. families. But this does not seem probable. It is more likely that this FAMILIES OF SCIENTIFIC MEN is confined to certain classes. To Cattell, in the Scientific Monthly, which classes is it confined and for what Vol. 4, page 248, has given some causes?

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