Germ-Cells in Chrysomelid Beetles, 251 



cells ; this body divided during the segmentation of the germ-band, 

 one half going to either side, where it lay in the dorsal region of 

 the second and third abdominal segiiients. Here the germ-gland 

 was enclosed in an epithelium of mesoderm-cells. 



GryUotalpa vidians was not so thoroughly studied as the other 

 species. Heymons, in this Orthopteron, found "nur sehr flache 

 Einstiilpung. Von dem Boden der Letzteren losen sicli Zellen los 

 und wandern ein. Ich bin geneigt, diese Zellen als Gesehlechtszellen 

 anzusehen, obwohl sie das Aussehen von Mesodermzellen haben und 

 ich ihr weiteres Schicksal nicht verfolgt halx^." 



6. Coleopiera. 



The Coleoptera are represented in the literature on the embryology 

 of insects by only a few papers ; of these eight contain fragmentary 

 accounts of the origin and early development of the germ-glands. 



Heider (1889) found that in Hydrophilus piceus the germ-glands 

 originated from the inner wall of the primitive abdominal segments 

 on either side of the body. They arose as solid outgrowths from that 

 part of the wall of the somites which lay between the place of origin 

 of the Fettkorperband" and the splanchnic layer of the mesoderm. 



The germ-glands of Leptinotarsa {Diwypliora) decemlineata were 

 described by "Wheeler (1889) as follows: ^'These organs originate 

 as two elongated thickenings of splanchnic mesoderm, one on each 

 side projecting into the body cavity. Later they become rounded 

 and are attached ])y a thin band of splanchnic mesoderm only." 

 Wheeler found several cells in the posterior anmiotic cavity of an 

 embryo of Leptinotarsa which he concluded might be comparable 

 to the pole-cells of Diptera. The origin and fate of these cells was 

 not determined. 



In Melolontha vulgaris, the sexual organs were found by Yoeltzkow, 

 (1889) "zu der Zeit, wo die Darmwulste sich am Bauch zu schliessen 

 beginnen und die Leibeshohle sich fertig gebildet hat. Sie werden 

 vom Mesoderm aus gebildet und liegen am hinteren Ende des Eies 

 als ein Paar birntThnnige Gebilde, umgebcn von einer starken, 

 ringformigen Zellenmasse mit grossen Kernen. . . Spater riicken 



