GERM CELLS IN THE ARTHROPODA 123 



It seems highly probable that the *'anello croma- 

 tico" of Giardina consists of chromatin, and Gold- 

 schmidt (1904) and others do not hesitate to class 

 it as an example of a " Chromidialapparat." Further- 

 more it is apparently the result of a chromatin- 

 diminution, as Boveri (1904) maintains, differing 

 from the similar process in Ascaris and Miastor in 

 details but not in the ultimate result. Finally, the 

 discovery of this peculiar body in Dytiscus adds one 

 more argument to the hypothesis that the chromatin 

 content of the germ cells differs from that of the 

 somatic cells quantitatively, at least in some cases, 

 and perhaps also qualitatively. 



Many are the bodies that have been homologized 

 with the " anello cromatico" of Dytiscus. Buchner 

 (1909) claims that the nucleolar-like structure in 

 the oogonia and young oocytes of Gryllus is homol- 

 ogous to both accessory chromosomes of the sper- 

 matogenesis and to this chromatin ring in Dytiscus. 

 This " accessorische Korper" passes intact into one 

 half of the oocytes where it disintegrates into granules 

 of a "tropische Natur." Foot and Strobell (1911) 

 have also compared it with the chromatin nucleolus 

 in the oogonia of Protenor with which it has certain 

 characteristics in common, but no such differential 

 divisions occur as in Dytiscus. 



Govaerts (1913) was unable to find anything 

 resembling the chromatic ring of Giardina, and con- 

 cludes that the formation of a chromatic mass dif- 

 ferentiating the oocytes and the nurse cells is unique 

 in the DYTISCID^E. His investigations demonstrate 



