Mitocliondria, Golgi Apimratm, and Yolk. 149 



Then possibly the nucleoli may produce " yolk " (Periplaneta ; 

 page 140) in certain insects. 



AMPHIBIA (Raoia). 

 Oogonium. Full-grown Oocyte. 



Mitochondria: 



._^ Definitive mitochondria. 

 --> Yolk bodies. 



Golgi apparatus > Golgi apparatus yolk 



(i.e. apparatus elements 

 slightly enlarged). 



On the Fate of the Mitochondrial and the Golgi 

 Apparatus Yolk Body during Embryogeny. 



The mitochondria can metamorphose into fat spheres or yolk 

 bodies during oogenesis. This probably means that the proto- 

 plasmic substratum which forms the basis of the mitochondrium^ 

 or which in the case of the Golgi apparatus is possibly the archo- 

 plasm, becomes loaded with fatty substance, phosphorized or 

 otherwise. This metamorphosis leads to the granules in question 

 becoming inert, and chromophobe with most dyes. 



Now, during organogeny the yolk bodies are drawn upon to 

 provide the energy for development, and they become smaller and 

 smaller. A question is whether the yolk granule formed from the 

 mitochondrium, or from a part of the Golgi element, changes back 

 to its former state, or again metamorphoses into a protoplasmic 

 granule ? This is a point to the elucidation of which future work 

 on the minute cytology of the embryonic tissues alone can give an 

 answer. „ 



Chromidia in Metazoan Oogenesis. 



The word " chromidium " is used by protozoologists to mean a 

 small, generally "solid" body, composed of true chromatin and 

 lying in the cytoplasm of the cell. In Arcella, for instance, the 

 presence of true chromatinic chromidia at certain stages in the life 

 cycle of this protist cannot be doubted. As Dobell has noted in 

 his paper (6), workers on metazoan cytology, of whom Popoff is an 

 example, have erroneously identified various structures as true 

 chromidia ; Popoff identifies what we now know to be the Golgi 

 apparatus of the Mollusc spermatocyte as the chromidia (34)' 



Many workers on oogenesis have wrongly identified the egg 

 mitochondria as chromidia : * this misinterpretation has been due 



* Can chromidia metamorphose into mitochondria ? Does the plasmosome 

 of the nucleus arise from chromatin, and can nucleolar substance give rise to 

 mitochondria ? These questions are all more or less intimately related, and still 

 unanswered. 



