EXPERIMENTS WITH CHRYSOMELID BEETLES. 



241 



out in order to learn whether or not germ cells would appear in 

 embryos if the germ cell determinants were prevented from taking 

 part in their development. Certain data regarding these experi- 

 ments are listed in Tables I. and II. Eggs were oriented as 

 soon as laid and the central region of the posterior end of each 

 was touched with a hot needle, thus killing the protoplasm just 

 beneath in which the germ cell determinants were embedded. 

 Since it was impossible to see the germ cell determinants in the 

 living egg, a rather large area had to be killed in order to be certain 

 that all of them had been reached. As noted above, the experi- 

 ments in removing the germ cell determinants by pricking the 

 egg and allowing them to flow out were not entirely successful 

 because it was never possible to tell whether all of them had 

 been obtained. 



TABLE I. 



EXPERIMENTS IN KILLING THE GERM CELL DETERMINANTS. 

 Leptinotarsa decemlineata Series L.D. 09. 



TABLE II. 



EXPERIMENTS IN KILLING THE GERM CELL DETERMINANTS. 

 Leptinotarsa decemlineata Series L.D. 018. 



Many of the eggs operated upon in experiments L.D. 09 and 

 L.D. 018 did not develop at all or developed abnormally. Under 



