148 



ZOOLOGY 



fuging ; secondly more abundant (this is certainly not true in 

 some cases, e.g., Patella, vide Brambell, supra) heavy ordinary 

 yolk (presumably albuminous in nature). The former he is 

 inclined to associate in formation with the Golgi apparatus, while 

 the latter he suggests is formed otherwise. (In justice to Bowen 

 it should be pointed out that he is concerned chiefly with the 

 Golgi apparatus, and that omissions of statements concerning 

 other inclusions is due to this.) 



The possible methods of yolk formation are practically as many 

 as the number of workers. They can, however, be grouped into 

 about two main groups. As a preliminary, it is necessary to 

 point out that it is practically impossible to discuss work in which 

 only one type of yolk in invertebrates is acknowledged. This 

 holds particularly for the earlier workers who failed to distinguish 

 between the fatty or lipoidal yolk and the albuminous or protein 

 yolk. Their facts can, however, be taken as evidence that one or 

 other type of yolk has been observed to be derived in a particular 



manner. 



Gatenby 



Hogben 



5J 



SUMMARY OF YOLK FORMATION 



1919 Ajpanteles 



1920 



Gatenby and 

 Woodger. 



5J 



J» 



1920 

 1920 



Synergus 

 Formica 



1920 Periplaneta 

 1920 Libellula 



1920 Helix 



Limncea 

 Patella 



No fatty yolk. 



Albuminous yolk by inter- 

 action of mitochondria 

 and secondary nuclei. 



Albuminous yolk probably 

 from secondary nuclei 

 from nucleolus. 



Albuminous yolk from 

 nucleolus. 



Albuminous yolk from 

 nucleolus bv interaction 

 of mitochondria and Golgi 

 bodies. 



Yolk from Golgi bodies or 

 cytoplasm. 



Yolk by Golgi bodies. 



