404 EMBRYOLOGY, 



There are also two different interpretations concerning the develop- 

 ment of the cortical substance. Balfour, Braun, Brunn, and Mit- 

 SUKURI derive it from accumulations of connective-tissue cells, which 

 are formed at the anterior portion of the primitive kidney along the 

 course of the inferior vena cava and the cardinal veins. According 

 to Janosik, Weldon, and Mihalkovics, on the contrary, the cell- 

 accumulations are either directly or indirectly formative products of 

 the epithelium of the body-cavity. I say " direct or indirect " because 

 in details the results of the three investigators named differ somewhat. 

 According to Janosik and Mihalkovics, it is the germinal epithelium 

 in the anterior portion of the genital ridge that furnishes by its 

 proliferation the material for the suprarenal body. Mihalkovics 

 therefore calls it " a detached part of the sexually undiflferentiated 

 genital gland, which consequently remains at a primitive stage of 

 development." Weldon, on the contrary, brings the suprarenal 

 body into relation with the most anterior part of the primitive 

 kidney. According to his representation, which appears to me to 

 deserve especial consideration, and from which indeed other researches 

 will have to begin, tlie sexual cords of the primitive kidney are concerned 

 in the formation of the suprarenal bodies. When, at the head-end of 

 the kidney, they sprout out of the epithelium of the Malpighian 

 glomerulus in the manner previously (p. 383) described, they divide 

 into two branches. One of these grows ventrally into the fundament 

 of the sexual gland, the other turns dorsally and spreads out in the 

 vicinity of the vena cava. 



Moreover, even Mihalkovics describes a connection of the sexual 

 cords with the fundament of the suprarenal body at certain places, 

 but makes both arise from proliferations of the epithelium of the 

 body-cavity. The connection is subsequently destroyed by the inter- 

 polation of blood-vessels. 



For the solution of the still pending questions most is to be expected 

 from the investigation of non-amniotic animals. 



During its development the suprarenal body is for a time of very 

 considerable size. In Mammals it temporarily covers the much, 

 smaller kidney, as in the human embryo of the eighth week repre- 

 sented in fig. 220, in which at the left the suprarenal body {nn) is 

 to be seen in its normal position, whereas on the right it has been 

 removed to disclose the kidney (n). Afterwards its growth does not 

 keep pace with that of the kidney ; however at birth (fig. 208), when 

 it already rests upon the latter (w) as a crescentic body {nn), it still 

 is larger in comparison with the kidney than it is in the adult. 



