Gcnu-Cclls in Chrysomelid Beetles. 279 



(18GU), lialbiani (lbS5) and Kitter (1890), in the Diptera, and 

 Huxley (1858), Metsclmikuff (1866), Balbiani (1866), Witlaczil 

 (1884) and Will (1888), in the Hemiptera, describe a precocious 

 segregation of the germ-cells. In the Diptera no active migration 

 is reported after the pole-cells re-enter the egg; in the Hemiptera 

 no movements have been noted at any stage in the history of the 

 germ-cells. 



The primitive germ-cells of several species of Orthoptera are, when 

 first seen, in the act of penetrating the walls of the coelomic cavities 

 {Blaita, Cholodkovsky, 1891, and Heymons, 1891; Xiphldium. 

 Wheeler, 1893). As noted elsewhere in this paper, Heymons (1895) 

 has established a much more extensive migration of the germ-cells 

 in Blatta and other allied forms than was described by the authors 

 named. A migration similar to that found in Blatta occurs in 

 Forficula (Heymons, 1895). 



The migration of the germ-cells in the Aptera has been recorded 

 by two observers, Heymons (1897) and Claypole (1898). The 

 former found that the germ-cells in Lepisnm have an ectodermal 

 origin at the posterior end of the germ-band. They soon '"sich zer- 

 streuen und einzeln, zwischen und neben den Mesodermzellen nach 

 vom wandern." The germ-cells are less favorable for study in 

 Lepisma than in Periplaneta, but Heymons nevertheless convinced 

 himself "dass die Wanderung der Ge^chleehtszellen sich ganz ahnlich 

 wie bei den Orthopteren voUzieht." According to Claypole (1898) 

 the germ-cells of Anurida move into the yolk at a late embryonic 

 stage and begin to mingle with its globules. Under high magnifica- 

 tion "the peculiarly 'succulent' character of the ceys" could be seen. 



Carriere and Burger (1897) describe in the Hymenopteron, 

 ChalicodonKt, the migration of the germ-cells from the third and 

 fourth abdominal segiuents into the fifth. 



In the "drone eggs" of the hee, the germ-cells penetrate the walls 

 of the primitive somites and congregate in the coelomic cavities. 

 (Petrunkewitsch, 1908). 



Although Woodward (1889) correctly observed the place of origin 

 of the germ-cells in the Lepidopteron, Vanessa, it remained for 

 Schwangart (1905) to follow their further history. In Endromis 



