EFFECTS OF REMOVING THE GERM-CELL DE- 

 TERMINANTS FROM THE EGGS OF SOME 

 CHRYSOMELID BEETLES. PRELIM- 

 INARY REPORT. 1 



R. W. HEGNER. 



A number of experiments were made during the spring and 

 summer of 1908 in order to test the conclusions reached in a 

 previous study of the origin and early history of the germ-cells 

 in Ccdligrapha inn/tipitnctata and several other chrysomelid 

 beetles. These experiments suggested some interesting hypoth- 

 eses which will be verified or disproved as soon as more material 

 can be obtained. The work was begun at the Zoological Lab- 

 oratory of the University of Wisconsin and continued at the 

 Marine Biological Laboratory, Woods Hole, Mass., 2 and at the 

 Zoological Laboratory of the University of Michigan. 



In a paper soon to be published 3 I have shown that there is 

 an intimate connection between the primordial germ-cells and a 

 disc of granules lying near the posterior end of the eggs of Cal- 

 ligraplia vntltipiinctata, C. bigsbyana, C. lunata and Lcptinotarsa 

 deceinlineata. This study led to an attempt to secure confirma- 

 tory experimental evidence. A brief account of the structure of 

 the beetle's egg and the early history of the germ-cells is neces- 

 sary for a clear understanding of the method of procedure and of 

 the results. 



The freshly laid eggs of these beetles consist of a thin pe- 

 ripheral layer of cytoplasm (the " Kleimhautblastem " of Weis- 

 mann) and a relatively large central mass composed of yolk 

 globules with a small amount of cytoplasm filling the inter- 



1 Contributions from the Zoological Laboratory of the University of Michigan, No. 

 120. 



2 The writer is indebted to theWistar Institute of Anatomy and Biology for the use 

 of a room at the Marine Biological Laboratory, Woods Hole, Mass., during the sum- 

 mer of 1908. 



3 " The Origin and Early History of the Germ-Cells in some Chrysomelid Beetles." 

 Accepted for publication by \ht Journal of Morphology . 



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