STUDIES ON GERM CELLS 459 



cleavage, when this mass forms part of the smaller entodermal 

 cell. In Lepas there has also been recorded (Bigelow, '02) a 

 segregation of granules in one blastom'ere. Many other sub- 

 stances, granular in form, have been described in the eggs of 

 animals, some of them at least having migrated there from the 

 somatic tissue. Blockmann ('87) discovered a number of bacteria- 

 like rods in the undeveloped eggs of Blatta germanica; these rods 

 multiplied by division and were considered symbiotic bacteria. 

 'Bacterienartige Stabchen' were also noted by Heymons ('95) 

 in the eggs of Periplanata orientalis and Ectobia livida; these 

 sink into the yolk and disappear. More recently a report of 

 Buchner ('12) indicates that these bodies are really organisms 

 which seem to be symbiotic and not parasitic, although it re- 

 mains to be proved what advantage the host receives from their 

 presence. Of a similar sort are the Zooxanthellae which Mangan 

 ('09) has shown enter the developing ovum from the parental 

 tissues. All of these organisms become in some way imbedded 

 in the germ cells, but, so far as we know, nevej* serve to distinguish 

 the Keimbahn, although a more selective distribution within 

 the developing animal would obviously be greatly to their ad- 

 vantage. 



Vander Stricht ('11) has compared the 'besonderer Korper' 

 found by Elpatiewsky ('09, '10) in the egg of Sagitta with several 

 bodies, the 'corps enigmatique,' which he discovered in the oocyte 

 of the cat (fig. 23, A). One or two of these 'corps enigmatique' 

 are present in the young oocyte originating from a few (one to 

 five) cytoplasmic safraninophile granules which are visible at the 

 beginning of the growth period. At first they lie near the nucleus, 

 but as the size of the oocyte increases, they become situated near 

 the periphery. Usually three parts can be recognized in the 

 'corps enigmatique:' "granulation centrale, couche intermedi- 

 aire et couche corticale foncee." As the term applied to them 

 indicates, the functions of these bodies were not determined. 

 The following suggestion is, however, made: "il est possible que 

 cet element nous montre, des I'origine, la 'Keimbahn' ainsi que 

 les premieres cellules genitales constituees" (p. 425). 



