No. 458.] PARTHENOGENESIS. 73 
Weismann’s theory in my observation that in parthenogenetic 
eggs the polar cells, after a copulation similar to that of the 
pronuclei, give origin through successive divisions to many cells 
which may be easily traced as far as the gastrulation stage of the 
embryo. My attempt to trace them still farther and to show that 
the male sexual glands in bees develop from these cells, has met 
with much criticism and requires confirmation. Doncaster, how- 
ever, was able to prove in Nematus the accuracy of my observa- 
tions as far as the beginning of the blastoderm stage. Although 
I am still, and until convinced of error shall remain, an adherent 
of Weismann's theory, I admit that the Sutton-Boveri theory 
would be strengthened, if it could be shown with certainty that 
I was at fault in my observations, and that the sexual glands of 
the drones develop not from polar cells but from the pronucleus. 
Future research will reveal the truth, but one thing is already 
certain: in all parthenogenetic eggs hitherto studied, with possi- 
bly the one exception of Nematus (according to Doncaster), the 
number of chromosomes in the first cleavage nucleus becomes 
in some way equal to that in the somatic cells. This is not 
limited to animals, but applies equally well to plants! and is 
consequently of fundamental importance. Yet it is not impos- 
sible that in Nematus there is no reduction in spermatogenesis, 
Which would lead to the same thing. 
It is clear that to reach a solution in the problems connected 
With the two theories of which I speak, we ought not to limit 
our research to observation of normal parthenogenesis alone, but 
rather to supplement such observation by the use of experiment. 
Here two methods are possible, of which one is cross-breeding 
and inbreeding, the other, artificial parthenogenesis and mer- 
ogeny. Much light could be gained by experiments in the for- 
mér upon animals like the bees, since such experiments would 
have many advantages over sintilar ones made on animals 
developing by fertilization only. Although this method prom- 
ises much, it has never yet, I regret to say, met with scientific 
application. ; | 
By fertilizing enucleated eggs we obtain development by mer- 
! Compare the observations of J. B. Overton (:04) on Thalictrum purpurascens. 
