lix 
precisely reproduce the conditions of one of the so-called germ- 
chambers from the ovarian tubes of a female insect.” 
It is therefore evident that the developmental history of these 
pseudova follows the same course as other insects’ eggs, which 
indeed I have elsewhere attempted to show is the case in all other 
groups of insects which possess the power of agamic reproduction: 
It may be added that the subsequent development accords in 
essential points with that which has been observed in other insects. 
Miastor appears indeed to be a very favourable subject for such 
investigations, and has yielded to M. Mecznikoff the remarkable 
discovery that the mysterious “ polar cells,’ which have been ob- 
served by so many naturalists and in such different groups of 
animals, re-enter the blastoderm, and finally pass into the germ- 
stock of the young larva. They thus apparently answer to the 
so-called “ embryonal male organ” of M. Balbiani. 
Prof. Leuckart, as we have seen, has clearly shown that the repro- 
ductive bodies in the larve of Miastor arise in the ovary, that they 
possess the rounded form, the germinal vesicle and spot, the vitel- 
ligenous cells, and in fact “all their first stages of development, in 
common with eggs.” He is not, however, yet prepared to follow out 
his own views to their logical conclusion, but, as he says, “ cannot 
quite determine to describe them aseggs. . . . . Just as the 
larval forms of an animal cannot be placed on the same level with the 
fully developed creatures, and regarded as such, so we must not 
transfer the denomination ‘ eggs’ to structures which have only their 
first stages of development in common with eggs.” These first 
stages, however, comprise just the special characteristics ; the sub- 
sequent changes, such as the development of the chorion, &c., are 
mere external adaptations for the purpose of enabling the egg to 
brave its exposure to external circumstances. The ovum in Mam- 
malia needs no such protection, and is not more specialized in this 
direction than that of Aphis or of Miastor; but no one would 
deny that the reproductive bodies of Mammalia are true ova. 
If, moreover, we examine the reproductive bodies throughout the 
animal kingdom, we may find every gradation from the most 
specially developed egg—that, say, of a bird—to that of the vivi- 
parous Aphis or Coccus. One great difference between an egg and 
a bud is the place of origin, to which, as it seems to me, Prof. 
Leuckart does not attach sufficient importance. 
He is, however, inclined to adopt the name of pseudovum for the 
