410 ROBERT W. HEGNER 



the Jiuclei c and d are in the anaphase and a and h in the telo- 

 phase stages of mitosis. The egg from which figure 49 was made 

 contained eight energids; that represented by figm-e 50 possessed 

 sixteen. So far as could be determined the nuclei of these ener- 

 gids are all alike. One of them is shown in figure 52. One hun- 

 dred and thirty-three nuclei were counted in the egg shown in 

 figure 51; these are still alike. Soon after this stage is reached 

 part of the energids move out to the periphery and fuse with the 

 'Keimhautblastem' to form the blastoderm (fig. 7, 5), whereas 

 the rest remain behind among the yolk globules and become 

 vitellophags. Those energids which encounter the pole-disc 

 do not take part in the blastoderm formation but become the 

 primordial germ cells. 



Does a chromatin-diminution process occur in Chrysomelid 

 eggs? The fact that part of each chromosome is cast out into 

 the cytoplasm in all except the 'stem-cell' during the early cleav- 

 age of Ascaris is well known (fig. 19, p. 442). A similar process 

 was described by Kahle ('08) in Miastor metraloas and confirmed 

 by me (Hegner, '12) in Miastor americana (fig. 3, p. 392). This 

 chromatin-diminution process results in the formation of a single 

 primordial germ cell containing the complete amount of chroma- 

 tin and a number of somatic cells with a reduced amount of 

 chromatin. The origin of the germ cells has been carefully 

 studied in a number of forms which in other respects resemble 

 Ascaris and Miastor, but in none of them has such a process 

 been discovered. Hasper ('11) was unable to estabhsh it for 

 Chironomus which is very similar to Miastor in early develop- 

 ment, nor has such a phenomenon been found in Sagitta (Elpat- 

 iewsky, '09, '10; Stevens, '10;Buchner, '10a, '10b) and the cope- 

 pods (Haecker, '97, Amma, '11) and Cladocera (Kuhn, '11, '13) 

 which undergo total cleavage and are otherwise similar to Ascaris. 



The nuclear divisions in the eggs of Chrysomehd beetles have 

 been examined by the writer with considerable care, but nothing 

 resembling a diminution process was found. Furthermore, there 

 are no evidences of chromatin bodies in the cytoplasm or yolk 

 as in Ascaris (fig. 19) and Miastor (figs. 33, 34, cR) where the 

 cast-out chromatin does not disintegrate immediately, but can 



