EXPERIMENTS WITH CHRYSOMELID BEETLES. 



245 



part of the " Keimhautblastem " which remained alive after the 

 operation, became supplied with nuclei, was broken up into cells, 

 and proceeded to develop that particular part of the embryo 

 to which it would have given rise if the rest of the egg had not 

 been killed. 



Two other series of experiments, L.D. 07 and L.D. 08, were 

 performed to test these results and in every case the living part 



of the egg developed as though the entire 

 egg were intact. None of the tissue that 

 is normally produced by the killed portion 

 was regenerated by the living material. 

 The embryos developed up to the time of 

 hatching, but were unable to break out of 

 the chorion. 



KILLING PARTS OF EGGS IN THE 

 BLASTODERM STAGE. 



FIG. ii. Ventral 

 view of an egg of Lep- 

 tinotarsa decemlineata 

 (L.D. 09 64). The pos- 

 terior end (k) was killed 

 just after deposition (see 

 Fig. i); a normal head 

 (/z) and part of the tho- 

 rax (/) developed from 

 the material which re- 

 mained alive, y, yolk. 



The eggs used for the experiments 

 designated as series L.D. 04 (Table IV.) 

 were laid at 4 P.M. on June 16, and 

 operated upon at 4 P.M. June 17. They 

 were, at the time of the operation, in a 

 stage similar to that of the egg shown in 

 Fig. 2. As indicated in Table IV., two 

 kinds of operations were performed; the 

 anterior part of one half of the eggs was 

 killed with a hot needle, and the posterior part of the other half 

 was killed in a like manner. Three preparations have been 

 selected to show the results of these experiments, (i) L.D. 

 04 A2, Fig. 12, (2) L.D. 04 AS, Fig. 13, and (3) L.D. 04 63, 

 Fig. 14. 



The embryos shown in Figs. 12 and 13 developed from eggs 

 which had their posterior parts killed, and were fixed four days 

 and seven days later respectively. One of these embryos (Fig. 

 12) consists of a head and thorax which appear to be normal in 

 every respect, and are as fully developed as these parts in a 

 normal embryo at a similar age (five days). The abdomen of this 



