Germ-Cells in Chrysomclid Beetles. 245 



sich selir lebliaft uiid stellen bald einen rundlichen Zellenhaufen, die 

 Geschlechtsanlage, dar, welcbe in dieser Gestalt wahrend der nachsten 

 Entwicklungsstadien verharrt. 



"Die Gesclileclitszellen liegen aiif der Grenze zwiscben dem Ento- 

 derm, dem Ectoderm der Baucbplatte imd dem gleicb sich bildenden 

 Mesoderm. Ueber ibre Zugehorigkeit zii einem der drei Keimblatter 

 liisst sicb streiten; mir geniigt es vollkommen, zu constatiren, dass 

 wir in ibnen indifferente Gebilde vor uns habcn, die gerade dort 

 entsteben, wo die drei Keimbliitter an einander stossen." 



4. Hymenoptera. 



The Hymenoptera are represented in tbe literatnre of insect em- 

 bryology by numerous papers chiefly on tbe bee. With the excep- 

 tion of the male of Apis (Petrunkewitsch, 1901) tbe germ-cells have 

 not been traced back to as early a stage as in several other orders of 

 insects. 



Ganin (1869) was the first to investigate the germ-glands of the 

 Hymenoptera. In Platygaster the rudiments of tbe germ-glands were 

 described at the end of the first larval instar as separate thickenings 

 on either side of the posterior end of tbe germ-band near the hind- 

 intestine ; between them arose a temporary unpaired elevation, "Ge- 

 schlecbtshugel," which disappeared during the second larval instar. 

 In another Hymenopteron Polynema, Ganin found that tbe germ- 

 glands developed from tbe undifferentiated cell mass of tbe tail-fold, 

 and lay in the cavities of the last abdominal segments, where they 

 remained during the larval period. 



Biitschli (1870), in his work on the bee, described in a well devel- 

 oped embryo "niebt weit von den Rlickenrandern der Leibeswandung 

 jederseits eine durch ungcfiihr 5 Segmente sich erstreckende langlicbe 

 Zcllenmasse aus dicht gedriingten rundlichen mit grossen Kernen 

 ausgestatteten Zellen bestehend," which be considered tbe iiidiments 

 of the germ-glands. Biitschli distinguished two layers in tbe germ- 

 band of tbe bee, from the inner one of which, the entomesoderm, the 

 primitive germ-cells Avere supposed to be derived. 



Uljanin (1872), according to Brandt (1878), found in tbe larva 



