248 



Notes on the Wolffian Body of Higher Mammals 



in lower vertebrates. Between the anterior and posterior parts there is 

 a space of five or six sections, each 20 // thick. 



In a somewhat older embryo, LXXX (V. B. 4.5, K. B.' 5.; probable 

 age 3 weeks), a slightly more advanced stage in the development of the 

 tnbules is noticed. The urinary apparatus begins opposite the 7th 

 myotome as a small duct. This extends for 4 sections, each 30 fj. thick, 

 and then ceases. During its course one small, blind, slightly curved, 

 tubule is given off. In the next four sections no trace of this duct can 

 be made out. In the section following, however, another duct starts 

 and is continued to the posterior end of the body. It seems at first 

 probable that this interruption in the duct may be due to a misplace- 

 ment of four sections in the series ; but a <3lose examina- 

 tion shows that this is quite impossible. Furthermore, 

 the tubule which arises from the anterior duct proceeds 

 from its ventral side and curves with its convexity ven- 

 tralwards; while the tubules of the posterior duct all 

 arise from the dorsal side of the duct with the con- 

 vexity dorsalwards, as shown in Fig. 3. 



There are no glomeruli opposite the anterior duct; 

 while in the posterior part of Wolffian body proper, there 

 is a glomerulus corresponding with each tubule. The 

 tubules are curved as represented in Fig. 3 and number 

 15 on one side of the body and 17 on the other. There 

 proved to be 17 glomeruli on one side and 18 on the 

 other. Considering the possibility of error in counting 

 these by following them through a series of sections, it 

 seems that the organ is a fairly symmetrical one; and 

 that there are approximately as many tubules as glomer- 

 uli, and an equal number of each on the two sides, 



A very similar condition is met with in another em- 

 bryo, LXXVl (T. B. 4.8, probable age 3 weeks). Here 

 also the urinary apparatus consists of an anterior and a 

 Opposite the 7th myotome the duct first appears. At 

 the upper end of the 8th it ceases, and a new duct begins at the lower 

 end of the 8th myotome. The latter duct extends backward to the 

 posterior end of the body cavity. The tubules have a structure simi- 

 lar to that described in the preceding embryo. There is no differ- 

 entiation into a secretory and a conducting part, Fig. 4. As nearly 

 as can be determined there are 19 tubules in the Wolffian body 



Fig. 3. Diagram- 

 matic reconstruc- 

 tion of urinary ap- 

 .paratus in Iniman 

 enibrvo. LXXX, 

 (V. B., 4-5.N. B.,5) 

 Lettering as above. 

 Gm, glonierules. 



posterior part. 



■•^ V. B. and N. B. refer to the vertex-breech and the neck-breech measurement. 



