144 GERM-CELL CYCLE IN ANIMALS 
nucleus with sixteen chromosomes, the “ Richtungs- 
kopulationskern”’ passes through three divisions, 
giving rise to eight “ doppelkernige Zellen.”” After 
the blastoderm is completed, the products of these 
eight cells lie in the middle line near the dorsal surface 
of the egg, where the formation of the amnion begins; 
the nuclei of these cells are small, and lie embedded 
in dark staining cytoplasm. Later they are found 
just beneath the dorsal surface near the point of 
union of the amnion with the head-fold of the em- 
bryonic rudiment. They are next located between 
the epithelium of the mid-intestine and the ectoderm ; 
from here they migrate into the ccelomic cavities, 
and finally, at the time of hatching, form a “ wellen- 
artigen”’ strand, the germ-gland, extending through 
the third, fourth, fifth, and sixth abdominal segments. 
The fertilized eggs of the bee were also examined 
by Petrunkewitsch, but no “ Richtungskopulations- 
kern” was discovered. In these eggs the genital 
glands arise from mesoderm cells. Doubt was 
immediately cast on these results, although Weismann 
(1904, p. 336) vouched for their accuracy. Thus 
Wheeler (1904) says, “‘ Even in his first paper there is 
no satisfactory evidence to show that the cells re- 
garded as derivatives of the polar bodies in the figures 
on plate 4 are really such, and not dividing cleavage 
cells or possibly vitellophags. ... When we take 
up the second paper we wonder how anybody could 
regard the figures there presented as even an adum- 
bration of proof that the testes of the drone are de- 
veloped from: the polar bodies.” Dickel (1904) 
