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XVIII. On the Ova and Pseudova of Insects. 
By John Lubbock, Esq.^ F.B.S., F.L.S., F.G.8. 
Eeceiyed November 10, — Eead December 9, 1858. 
If, in his celebrated work on “ Alternations of Generations,” Professor Steenstrup has 
not succeeded in explaining the phenomena of asexual reproduction, he has at least the 
great merit of having brought together many interesting observations, the relations of 
which had remained unrecognized up to his time. The value of his suggestions is well 
shown by the number of memoirs which in the last few years have appeared on this 
subject, and by their having produced a discussion in which almost every naturalist has 
taken some part. It is, however, perhaps not going too far to say that as yet no 
satisfactory explanation of the phenomena has been suggested, and that we are now 
just as far from knowing as we were twenty years ago, what are the different conditions 
under which some eggs remain undeveloped unless they are brought under the influence 
of the spermatozoa, while others contain within themselves the power of producing 
young without the necessity of any external stimulus. Still, though we have been 
unable to obtain any insight into the philosophy of the subject, we have in this period 
collected together a great mass of facts which will perhaps ere long lead us to some 
satisfactory conclusion. 
In a paper “On the Double Method of Eeproduction in I)aq)hnia*” I lately 
endeavoured to show that eggs and buds are in fact identical, that they are the two 
extremes of a long series, and that therefore every intermediate gradation between them 
will probably exist or has existed in nature. I however suggested that it would pro- 
bably “ be convenient to apply some distinguishing name to those eggs which do not 
require impregnation as a necessary antecedent to development,” and Professor Huxley 
has since proposed to call them Pseudovaf. 
This name seems to me very appropriate, and I intend therefore to adopt it, merely 
repeating that we cannot, in my opinion, draw any definite line between eggs on the 
one hand and pseudova on the other, and that in the Bee and many Lepidoptera the 
same body is capable of becoming either the one or the other. 
In the above-mentioned memoir, I described at length the development of the agamic 
eggs, or pseudova, of Baphnia, in order to show that it is essentially the same as that of the 
ordinary eggs of a Crustacean. Professor Huxley, however, has since presented to the 
Linnean Society an excellent work on the ova and pseudova of Aphis, and shown that in 
this genus at least there are important differences between the ovarian development of the 
ova, and that of the so-called internal buds or pseudova ; and he suggested to me that it 
* Philosophical Transactions, 1857. f Linnean Transactions, vol. xxii. p. HI. 
MDCCCLIX. 2 Z 
