GERM CELLS OF GRYLLOTALPA 305 



into the cytoplasm and also around the nucleus (plate 4, G). 

 At this time there is a sharp line of demarcation between the 

 mitochondria and the peripheral cytoplasm. As growth con- 

 tinues, the mitochondria move further out into the cytoplasm 

 and the line of demarcation becomes less distinct (plate 4, H). 

 Finally, at a later stage, before the appearance of the yolk in the 

 developing egg, the mitochondria appear as minute granules 

 equally distributed throughout the cytoplasm (plate 4, I). My 

 drawings have been made from the ovaries of Gryllotalpa vulgaris 

 (Naples) as here the mitochondria are much more sharply dif- 

 ferentiated. Their behavior is the same in Gryllotalpa borealis. 



C. Discussion of mitochondria 



The principal questions which arise in connection with a study 

 of mitochondria are: first, their origin; second, their continuity 

 or discontinuity; third, their fate; and fourth, their zoological 

 and physiological significance. Many suggestions have been 

 made in answer to these four questions. It is not my intention 

 to discuss the literature in detail, but merely to point out the 

 principal differences of opinion and then give my own tentative 

 conclusions, based on my observations in Gryllotalpa. For those 

 who wish a detailed and critical review of the literature in this 

 field, I refer them to that of Duesberg of 1911. 



In a study of the spermatogenesis of the mouse, Benda ('97) 

 observed some granules in the cytoplasm of the sex cells. He 

 followed these granules through the different stages of matura- 

 tion and into the spiral filament of the middle piece. While 

 earlier workers had seen these granules, Benda was the first to 

 describe them in detail and to ascribe to them any particular 

 significance. From this early observation and later ones Benda 

 concluded that these granules are specific cell organs of cyto- 

 plasmic origin; that they are present in all cells; that they are 

 carried into the egg by the spermatozoon and hence play a part 

 in heredity. To these granules Benda gave the name 'mito- 

 chondria.' While other names have been proposed and used, 

 some perhaps even more appropriate (chondrioconten, plasto- 



JOURNAL OF MORPHOLOGY, VOL. 28, NO. 1 



