IN BNt.n, JUNE 22, 1912.J NATURE AND N4URTURE. L MEDCA JouAr. 1439 = I is evidence for believing that colour-blindness,; haemophilia, pseudo - hypertrophic paralysis, and Leber's disease may very probably be included in the list of sex-limited diseases. In the known cases t3rttt' 1ebicat 3ourna. of transmission it is the males who inherit; the females transmit. In studying the transmission of disease the con- tributing factors of nature and nurture have to be SATURDAY, JUNE 22ND, 1912. carefully analysed and weighed. To arrive at an estimate of the proper contribution of the former is the main object of an inquiry into family histories, NATURE AND NURTURE. and Dr. MVott, in the article mentioned, shows the many pitfalls which beset attempts to arrive at just SINCE the days of Charles Darwin three names stand conclusions in nervous and mental out prominently as contributors to the advances diseases. He made gives a word of warning when he states that he is in the theoretical aspects of biological knowledge. " of that various These are the names of Francis opinion causes, such as alcoholism, Galton, Gregor infective diseases, auto-intoxications, physical injury, Mendel, and August Weismann. Not only has the especially head and shocks, individual work of each of these men been of vast injuries emotional shock, importance, but the wlhich their sexual excesses, and unnatural practices are too often impetus investiga- wrongly assigned as the sole cause of nervous and tions have given to researchl into all the many-sided mental disease, to the neglect of the problems of lhas been enormous. In inborn factor." hieredity this There is no doubt much truth in this. Alcohol may country at least the name of Bateson will also always be the cause in a certain number of cases of insanity hold a promninent place, since it is largely throualg him and the school whlichl he has established that the in persons without any hereditary taint; but it more work the Abbot Briinn readily affects those who have an inherited mental epoch-making of of has been weakness and in whom there is less power of control made familiar to us. As one outcome of this may be to withstand the mentioned the increased attention now to temptation. paid the Dr. AMott is evidently a strong believer in the facts of inheritance in relation to disease in the social potency of the inborn factor, and with this .s well as in the individual organism. belief In thus the of many biologists will be disposed to agree; but this accentuating importance the work of very belief raises the perennial question of the the so-called Mendelian school, there is no intention inheritance of acquired characters. Ever since the to minimize the value of the work done by the bio- publication of Weismann's theory of the germ metricians. The ultimate aim of both is the acquire- plasm, the possibility of the transmission of acquired ment of exact knowledge, the application of whiclh characters from parent to offspring has may lead to race betterment, but the very method of generallv been regarded as hiighlv improbable, if attacking the problems differs. The biometrician not impossible. There are iiot wanting signs at deals with statistics, with evidence in bulk. The the Mendelian inheritance in present time that many biologists are beginning investigates individual to waver, and a consideration of the facts of disease cases. The greater the number of cases recorded transmission would appear to have a direct bearing the more reliable the deductions, but the evidence upon the argument. is of necessity based on relatively smaller numbers. To say that a disease, or even the tendency to To mention but one instance, the inheritance of disease, is inherited is but to shift the problem 1rachydactyly. The evidence deduced from the re- a stage further back. Disease is not the normal ported cases is of great value, but from the biometric condition of a healtlhy organism, or to put it standpoint these cases are so few in number as to be another way, organisms were originally by nature of relatively little importance. It is for this reason healthy ; disease must therefore have been at its that the Mendelian principles of heredity appeal most inception an acquired character, that is to say, disease to the clinician, as he can individually, by the careful is a somatogenic character. Weismann defines and exact study of a few cases, materially assist in the advancement of knowledge. acquired or somatogenic characters as " those which The are not preformed in the germ, but which arise only investigation of these principles in their rela- through special influences affectiiig the body or tion to disease-transmission is one of the great individual parts of it. They are due to the reaction features of the past decade. In support of this it is of these parts to any external influences apart from only necessary to mention the work of Nettleship the necessary conditions of development." Many and Mott. In a recent number of Brain the pathological states at the very commencement of their latter has added yet another valuable contribution evolution must have satisfied this definition. If, then, to the subject from the clinical standpoint. In this disease cannot be entirely a matter of germinal varia- article Dr. Mott deals with the "inborn factors of tion, such variation must be due to influences nervous and mental disease," and gives a series of operating upon the germ plasm from without, that illustrative pedigrees. is, influences acting through the somatic cells. The Among the many results brought to light by a existence of such bodies as hormones furnishes a careful analytical inquiry into the facts of the possible explanation of how such influences might lhereditary transmission of disease not one is of take effect. Confirmation of the inheritance of greater interest than the discovery that certain acquired characters is to be found in Bordage's diseases are sex-limited-by which is meant that the observations on peach trees in the island of R6union.2 disease may be limited to one sex, but is transmitted This is no mere academic discussion, for, if disease at by the sex in which the disease does not appear. A its inception is a somatogenic character, then it is very remarkable and complete instance of such a possible that environment may originate it in an case has recently been published by Nettleship otherwise stock. showing the pedigree of congenital night-blindness healthy with Many writers at the present time appear to regard myopia.i In addition to night-blindness, there heredity as the last word in all matters appertaining I Trans. Ophtlial. Soc., vol. xxxii, 1912. I 2 Bxsll. scientifique de la France et de la Belgique, Tome 44. 1910. Tffz zsnmsu 1 1440 Y-RDICAL JOU'RWAL j RUSKIN ON THE -MEDICAL PROFESSION. LJUNE 22, 1912.. 1440 ~~~ZDICALJOUUWAL 3 RTJSKIN ON THE MEDICAL PROFESSION. [JUNE 22, 1912.~~~~~~~~~~~~~~~~~~~~~ to eugenics in the widest sense of the term. Some the general tendency is for insanity to die out in three enthusiasts are even clamouring for a health certificate generations-the power already exists to control the before marriage. Legislation, on the other hand, has insane therefore ilothing more is required. Upon hitherto ignored heredity and has regarded environ- every ground, therefore, the need is urgent for ment as the sole object of its attention. It is obvious statutory powers to deal with aments above the age that both factors must be taken into account con- of i6, and, above all, for the establishment of a central currently, not only in the study but also in the pre- board of control to superintend the care and manage- vention of disease. ment of aments and dements alike. Such a board was A further point to which Dr. Mott directs attention recommended by the Royal Commission. is what is called the " law of anticipation." Nettleship As yet there has not been time to keep records of has also previously discussed the matter. By this the hereditarily tainted for more than three genera- term it is meant that the manifestation of an inherited tions, except in a very few cases. It is of the greatest morbid change tends to appear at an earlier age in importance that they should be carriedl fuirther. successive generations or in the successive children of Adequate provision for the continuation of the in- the same parents. In this connexion Mott makes an vestigation is, no doubt, made in asvlums by the card important pronouncement as the result of his wide system, but this is not sufficient. The establishment experience. He says that he has "often observed of a statistical bureau connected with the local that there is a general tendency for inisanity not to authority of each of our large towns to keep, over proceed beyond three generations. There is frequently a period of several generations, a record, as far as either a regression to a normal type or the stock dies possible continuous, of all personis mentally affected, out. Not infrequently the stock dies out by the in- either aments or dements, would be of the greatest born tendency to insanity manifestinig itself in the value. It can hardly be doubted that the information form of congenital imbecility or in the insanity of so obtaiined would enable action to be taken whichl adolescence. Stuch patients, especially paupers, are would in the long run result in economies that prone to die of tuberculosis; thus rotten twigs are would much more than counterbalance the initial continually dropping off the tree of life." In support expenditure.