276 GERM-CELL CYCLE IN ANIMALS 



the nucleus ; these bodies have been given various 

 names such as spherules (Kunstler, 1882), cytomi- 

 crosomes (La Valette St. George, 1886), bioblasts 

 (Altmann, 1890), and ergastoplasm (Bouin, 1898). 

 In 1897 and 1898 Benda noticed the constant pres- 

 ence of certain granules in the male germ cells of a 

 number of vertebrates and was able to trace their 

 history from the spermatogonia until they formed the 

 spiral filament in the tail of the spermatozoa. These 

 observations were extended the following year 

 (1899) so as to include all stages in the development 

 of the eggs and spermatozoa of many vertebrates 

 and invertebrates and also various tissue cells such 

 as striated muscle-fibers, leucocytes, marrow-cells, 

 etc. This work attracted wide attention chiefly 

 for two reasons: (1) the history of the granules 

 was carefully worked out and the various stages 

 accurately described, and (2) special, rather com- 

 plicated, staining methods were devised which were 

 supposed to color the mitochondria so that they 

 could be distinguished from all other cell inclusions. 

 From 1899 until the present time an ever increasing 

 number of investigators have attacked the problems 

 presented by the mitochondria, or referred to these 

 structures incidentally when working upon other his- 

 tological or cytological problems. The study of mito- 

 chondria received its greatest impetus, however, 

 in 1908, when Meves published a paper on these 

 structures in the chick embryo entitled ''Die Chon- 

 driosomen als Trager erblicher Anlagen." In this 

 paper the chick embryo is described from the fifteen- 



