AUTHOR'S ABSTRACT OF THIS PAPER ISSCED BY THE BIBLIOGR.4PHIC SERVICE, FEBRUbRY 24

THE VARIATIONS OF THE INFERIOR OF THE DOMESTIC CLiT

HARRISON R. HUNT West Virginia Universitv

SEVEN FIGURES

The inferior thyroid of man vary considerably. The following observations, made on thirty-three domestic cats selected at random, show that the same is true of this vein in the cat. Each of the accompanying figures represents, some- what diagrammatically, the conditions in a single animal. These seven animals suffice to give a fairly complete idea of the variations in the remaining twenty-six. Figure 1 shows the inferior thyroid vein (I) communicating anteriorly with the left internal jugular, receiving branches from only the left lobe of the thyroid gland (14), then passing ob- liquely backward across the (13) to join the right innominate vein (10). The veins labeled 2 and 3 in this and the following figures were not homologized with certainty with the human superior and middle thyroid veins. Two other dis- sections resembled figure 1 very closely, except that in one of them the inferior thyroid vein joined the external at a. Figure 2 resembles figure 1 in some respects. However, the inferior thyroid vein (1) in figure 2 receives a branch (a) from the right lobe of the thyroid gland (14), empties into the right (a), but in the dissection did not appear to communicate directly with the left internal jugular. The inferior thyroid vein in a second cat joined the jugulars at m 39 40 HARRISON R. HUNT

(fig. a), and its transverse branch (fig. 2, a) could not be traced as far as the right lobe of the thyroid gland. In a third indi- vidual, vessels a and 3 (fig. 2) were connected by a conspicuous vessel running along the dorsal surface of the right lobe of the thyroid gland, and the inferior thyroid vein entered the right innominate at n (fig. 2). In all other respects the inferior thyroid veins in these three cats were very similar. Tn one case (fig. 3) the inferior thyroid vein (I) was formed by the union of a branch (2) from each of the internal jugular veins (4 and 5). The inferior thyroid, after receiving branches from the right lobe of the thyroid gland (Id), passed obliquely backward, joining the left innominate vein (11) near its union with the precava. The re~emblancebetween the inferior thyroid veins (I) in figures 3 and 4 is evident. However, in figure 4 the inferior thyroid apparently was unconnected, at its anterior end, with the internal jugular ireins; it lay close to the left lobe of the thyroid gland; and its junction with the left innominate vein was conLiderably anterior to the junction shown in figure 3. A snlall vein (fig. 4, 15) ran along the dorsal side of the left lobe of the thyroid gland parallel to the inferior thyroid vein (I), con- nccting anteriorly and potteriorly with the latter vessel. One other cat showed practically the same conditions $5 those repre- :ented in figure 4, though the vein 15 (fig. 4) was not found, and the inferior thyroid vein emptied into the innominate at a (fig. 4). In figure 5 the two vessels uniting to form the inferior thyroid vein (I) passed backward a short distance before coming together. The inferior thyroid vein was median in position, receiving small sidc: branches from both lobes of the thyroid gland (I,$). Except for the fact that 16 and 16 (fig. 4) lay on opposite sides of the trachea, their locations and courses were quite similar. In four other individuals the inferior thyroid vein strongly resembled the same vein in figure 5, though in one case it joined the precava at e (fig. 5). INFERIOR THYROID VEIN OF DOMESTIC CAT 41

2a II

22

I

2 4

EXPLANlTION OF FIGURE NUMERALS 1, inferior thyroid vein; 2 and 3, branches of the internal jugular veins; 4 right internal jugular vein; 6, left internal jugular vein; 6, right ; 7, left external jugular vein; 8, right subclavian vein; 9, left subclavian vein; 10, right innominate vein; 11, left innominate vein; 18, precava; 19, trachea; 14, thyroid gland. (For the significance of 15, 16, and the letters, see text.) 42 HARRISON R. HUNT

In the animal from which figure 6 was drawn a vein ran backward near the medial margin of each lobe of the thyroid gland (I4), the two veins uniting at the level of the isthmus of the gland. One of these vessels (2) branched off from the right internal jugular vein. The inferior thyroid vein (I) emptied into the innominate where the external jugular and subclavian veins joined (8). The variations of the inferior thyroid vein in thirteen more cats can best be described by reference to the lettering in figure 6. In twelve of these animals the vein branched at approximately the following points: in one case at a (the branching thus closely resembling the branching of the inferior thyroid vein in fig. 5), in four cases at c, in six animals at the place where the inferior thyroid vein branches in figure 6, and in one animal as far back as d. The approximate points at which the inferior thyroid vein in these thirteen cats emptied into the innominate and external jugular veins varied greatly (fig. 6). In four cases this union was at 0, in four cases at n, in two at 1, and in three cases at the points e, h, and i, re- spectively. In two of these individuals the left anterior branch could be traced to the left internal jugular vein; in two cases, including the animal shown in figure 6, the right anterior branch came from the right internal jugular vein. Incomplete records of the inferior thyroid veins in four animals show that the vein emptied on the right side in three of them, and into the left internal jugular in the fourth animal. Figure 7 represents the posterior end of the inferior thyroid vein (I) in one animal. The anterior portions of the vein were not drawn. The vessel divided into two branches which joined the innominate veins (10 and 11) at the places shown in the figure. Possibly some very small veins emptying into the inferior thyroid vein were not well injected in all the cats examined, thus escaping observation. This might explain the failure in many cases to find connections between the inferior thyroid and internal jugular veins near the anterior end of the thyroid gland. INFERIOR THYROID VEIN OF DOMESTIC CAT 43

TABLE 1

NUMBER OF CATS

Inferior thyroid vein unbranched at its anterior end...... 3 Inferior thyroid vein divided into two branches at the anterior end of the thyroid gland...... 6 Inferior thyroid vein divided into two branches at varying positions between the lobes of the thyroid gland...... 17 Inferior thyroid vein dividing into two branches posterior to the thyroid gland...... 1

TABLE 2

NUMBER OF CATS

Inferior thyroid vein emptying into left innominate...... 17

Number of cases in which the vein emptied on left side., ...... 18 Inferior thyroid vein emptying into right innominate...... 6 Inferior thyroid vein emptying into right external jugular., ...... 3 Inferior thyroid vein emptying into right internal jugular...... I Inferior thyroid vein emptying on the right side (exact position not noted) ...... 3

~~~~~~ ~ Number of cases in which the vein emptied on the right side...... 13 Inferior thyroid vein emptying into precava...... 1 Inferior thyroid vein emptying into both innominate veins...... 1

SUMMARY The results of this investigation may be summarized best in tabular form. Table 1 shows the variation in the dichotomous branching of the inferior thyroid vein at its anterior end. Table '2 summarizes the variations of the point at which the vein emptied posteriorly into the larger veinous trunks. Thus the inferior thyroid vein in the majority of cases branches between the lobes of the thyroid gland and enters the larger veins on the left side.

Idorgantown, West Virginia, November 22, 1918 Resumido por el autor, Eben James Carey.

Estudios teratolbgicos. A. Sobre un phocomelus, con especial menci6n de ]as extremi- dades. El caritcter principal de esta clase de monstruos es un acortamiento anormal y cesaci6n del desarrollo de algunos o todos 10s huesos largos de las extremidades. El presente estudio revela el hecho de que en ausencia completa o desarrollo rudi- mentario de una parte del esqueleto, se encuentra tambi6n una falta completa o parcial de 10s m6sculos relacionados con 61. Lo inverso es tambi6n cierto, pues un excesivo desarrollo de las partes esqueleticas estit acompafiado por un grado mayor de desarrollo en 10s mtisculos relacionados con ellas. B. La forma ex- terna de un embri6n humano anormal de veintitr6s dias. El autor da una detalla da descripcih de la forma externa de este embribn y una descripci6n de la interesante malformaci6n de la regi6n cer- vical. El estado de desarrollo de la forma exterior coloca a este embri6n entre el descrito por Bremer, de 4 111112. de longitud y 21 dias de edad, y el descrito por Mall, de 7 mm. y 26 dias, de mod0 que la edad probable del que se describe es 23 dias. C. y D. Las anomalias de 10s monstruos anencefitlicos: eranioraquis- quisis completa. El hecho mits interesante con relaci6n a 10s monstruos anencefitlicos, ya notado por varios observadores, es que generalmente pertenecen a1 sex0 femenino. Las anomalias bien marcadas, que se describen en 10s presentes estudios, son: la falta de cerebro, generalmente tambien de m6dula espinal y la falta de desarrollo de 10s huesos que integran la b6veda craneal y la litmina de la columna vertebral. La boca tipicamente abierta de 10s monstruos anencefitlicos est&relacionada con la falta de la- bbveda craneal y la p6rdida correspondiente de la porci6n ante- rior del mtisculo temporal. Las disecciones revelan tambi6n la existencia de una interrelacih definida entre el desarrollo de 10s tejidos 6seo y muscular.

Translation by Jod F. Nonidez Columbia University