346 



Xotes oil the Wolffian Body of Higher Mammals 



In forcing fiiiid into the tnbules of the Wolffian body it is necessary 

 to inject either through the allantois or the cloaca. In small embryos 

 it is easier to tie ofE the cloaca below the entrance of the Wolffian duct, 

 and fill the allantois with the injection mass. Then by gently squeez- 

 ing the allantois between the fingers the fluid can be forced slowly into 

 the tubules of the Wolffian body. In older embryos the cannula can be 

 placed in the cloaca, and the allantois tied off. Where possible this is 

 the best method, because the soft gelatinous tissues around the cloaca 

 make it difficult to close it in any way. It proved to be a most instruc- 

 tive thing to cause the injection mass to flow into the tubules slowly, 

 and to watch with a lens its course. Injections with lamp-black agar 

 and subsequent digestion with pepsin and hydrochloric acid were un- 

 satisfactory; for the delicacy of the structures made it impossible to 

 isolate complete tubules. 



The ordinary methods of histological study Avere employed. The 

 reconstruction was made by the Born wax-plate method. 



2. TtTBULAR System of Wolffiax Body in Humax Embryos. 



In all higher Amniota the first part of the urinogenital apparatus to 

 make its appearance is the Wolffian duct. According to Hensen and 



V. Spec this tube is de- 

 rived from the ectoblast; 

 Avhile His and Kowalews- 

 ky believe that it has its 

 origin in the middle plate 

 of the mesoblast. Eemak, 

 V. Kolliker, AValdeyer, 

 and others trace its de- 

 velopment from the lat- 

 eral plate of the meso- 

 blast. Romiti, Eensen, 

 Dansky, and others find 

 that it springs from the 

 ccelomic epithc4iiim. Ac- 

 cording to Michalkovics 

 it is at first a solid mass 

 of cells differentiated 

 from the mesoblast. The canal is blind at both ends in the beginning, 

 and becomes lined by an epithelium-like layer. 



- - -ha. 



Fio. 1. Transverse section of human embryo CLXIV 

 (3.5 mm.) in length. A. beginning- of anterior part of 

 urinary apparatus. W. D., V, olfflan duct. 



