SIEBOLD, ON PARTHENOGENESIS. 
227 
wliicli probably was only dependent upon the favorable or unfavorable 
consequences of my preparation of the eggs employed for observation. 
If the question is to be raised, why Leuckart was not so fortunate as 
to see what I have succeeded in seeing, I can make no other answer, but 
that probably the different method followed by us in our investigations, is to 
be blamed for Leuckart's want of success. Berlepsch informed me, that 
Leuckart did not examine the contents of the eggs by the careful com- 
pression of the bee's egg, but that he confined himself to submitting the 
eggs in a perfectly uninjured state to an external examination." 
He also obtained drone- eggs on the same occasion. Of the 
examination of these eggs he says — 
"I examined these twenty-seven drone-eggs, which might have been 
about twelve hours old, and which agreed perfectly both in their appearance 
and organization with the female eggs, with the same care and by the same 
method with which I had treated the female eggs, and did not find one seminal 
filament in any single egg^ either externally or internally. I must also add, 
that only the seventh, thirteenth, and twenty-third eggs were unsuccessfully 
prepared. In all the rest of these drone-eggs the yelk retreated slowly 
and completely from the upper pole of the egg-envelopes, after the bursting 
of the membranes ; the desired empty clear space between the micropylar 
apparatus and the retreating yelk was produced in the interior of these 
eggs, so that if seminal filaments had been present in them, they certainly 
would not have escaped my searching and inquisitive eye. In order to be 
quite satisfied as to this remarkable negative result, and to obtain the full 
signification of it, several female eggs of the same queen which had furnished 
these drone-eggs, were examined for comparison ; for the objection might 
certainly have been raised, that this queen might have laid nothing but 
barren eggs, as, being already weakened by age and near her death, she 
might have had no more spermatozoids in her seminal receptacle. Never- 
theless, many of these eggs contained seminal filaments ; they were the 
twenty-seven eggs already mentioned by me, — namely, the sixteenth to the 
forty-second eggs." 
It may be thought by some that these investigations are 
not conclusive, and perhaps they are not. But it should be 
remembered that the evidence on the other side is not 
a whit more conclusive. A naturalist confining his attention 
to the phenomena of sex as presented in the vertebrate 
animals, might bring against Von Siebold a verdict of not 
proven;" but one acquainted with the phenomena of par- 
thenogenesis in plants and the lower animals will be dis- 
posed to receive this evidence as of more value than the 
mere inference of the necessity of the influence of both 
sexes, derived from observations upon the higher animals. 
In fact. Parthenogenesis, in all its integrity, has now been 
observed- in a large number of cases in the vegetable king- 
dom. The occurrence of seeds, independent of stamens, was 
first observed in a Euphorbiaceous plant in the gardens at 
Kew. It has been subsequently observed in a large number 
