202 WILLIAM WALLACE. 



in fig. 21, it is difficult to see how blood-cells could have 

 gained access to the egg during its degeneration. In 

 Zoarces leucocytes only come upon the scene at a late 

 stage in the process, and then tlieir function is probably to 

 remove and convey into the blood or lymph channels the 

 ultimate products of the degeneration of the egg, viz. the 

 yellow non-adipose granules.^ 



5. Structural Changes in Ruptured Follicles. 



Forchammer and Rathke were aware of the fact that the 

 clavate villi of the pregnant ovary of Zoarces are not new 

 formations, but are developed directly out of ovigerous 

 pouches by hypertrophy of the tissues. Stuhlmann (1887) 

 compares in detail the two structures, viz. '^foUikcl" and 

 " zotte" (villus), especially in regard to tlieir vascular supply, 

 which he carefully studied both in injected preparations and 

 in sections. 



Stuhlmann's account of the structure of a villus and his 

 minute comparison of it with an ovigerous pouch are, however, 

 based on a misconception, owing to his having selected for 

 description not a typical or normal villus, i. e. an ovigerous 

 pouch from which an egg had escaped, but one in which an egg 

 had degenerated. That this is the case is perfectly clear from 

 Stuhlmann's description and figures. Stuhlmann speaks of 

 a peculiar tissue occupying the centre of the villus; he calls 

 it the " Narbengewebe," and describes it as "eine netzartige 

 protoplasmatische Grundmasse mit eingestrenten Kernen, in 

 der man zahlreiche Vacuolen sicht." In regard to the develop- 

 ment of this "Narbengewebe," Stuhlmann remarks that it may 

 have originated in the ruptured follicle (!) ; "sulir wohl durch 

 Degeneration des Follikelopithels und der angreuzenden 

 Gewebespartien.'^ This is clearly an error. A "protoplasma- 

 tische Grundmasse" with embedded nuclei and vacuoles is 

 always associated with the fatty degeneration of the egg, as I 

 ' See " Fat Absorplioii," in ' Scliafer's Pliysiology,' vol. i, p. 458. 



