70 EOBEET SCHAEFF. 



Although I have never seen prolongations from the follicular 

 cells pass through the zona, as has been described by Eimer 

 and Lindgren, I strongly believe that the follicle forms the 

 most important source for the nourishment of the egg. 



Lindgren 1 observed in the mammalian ovum that granulosa 

 cells occasionally travelled into the egg by means of the pores 

 of the zona. Some were seen inside the egg, and others halfway 

 out, and prolongations from the follicular cells were frequently 

 traced to the interior. I may mention that nothing of the 

 kind was noticed by me in the eggs of osseous fishes ; indeed, 

 the pores of the zona are much too narrow to allow of their 

 being traversed by the follicular cells. 



V. Development. 



On account of my not being able to obtain all the different 

 ovarian stages, I have made no observations on the origin of 

 the egg. Whether the ovum originates from a simple trans- 

 formation of an epithelial cell, or whether several unite, as in 

 Elasmobranchs, has not been observed. I believe, however, 

 that probably only one cell is concerned in the formation of 

 the egg. This view is held by Brock 2 and Kolessnikov. 3 The 

 former makes the following statement : — " We often find im- 

 mediately under the epithelium, and frequently in direct com- 

 munication with it, numerous masses of cells. These masses 

 are seldom utricular — more often they are round or wedge- 

 shaped. The cells show every gradation from epithelial cells 

 to the smallest ova. The whole process lasts only a very short 

 time." 



Kolessnikov also mentions that the primary eggs are formed 

 by the growth of some epithelial cells, one cell giving rise to 

 one ovum. A division of the ovum, as described by Waldeyer, 

 could not be found by the same author in either Amphibians or 

 Teleosteans. 



1 Lindgren, loc. cit. 



2 Brock, loc. cit. 



3 Kolessnikov, " Ueber d. Eientwicklung bei Batrachiern und Knochen- 

 fischen," 'Arch. f. mikr. Anatomie,' vol. xv, 1878. 



