636 
POPULAE SCIENCE EEVIEW. 
are identical, and tliat each is a series of improvements which Nature 
achieves in an animal she is leadmg to the mature condition. For 
the difference in the circumstances under which the two sets of changes 
take place, he accounts by the following law : — In certain ova, the 
supply of pabulum is inadequate to the changes which it is required 
that the animal shall undergo, and hence the young being is ushered into 
existence as a simple larva, capable of obtaining such a supply of nutriment 
as is necessary for the alterations it must undergo in reaching the final 
condition. Alternation of generations, or, as he terms it, geneagenesis, is also 
regarded by M. de Quatrefages as a species of complex metamorphosis. 
There is a good deal of ingenuity m the way in which jVI. Quatrefages en- 
deavours to demonstrate his vie'^^s ; and his happy method of illustration, 
and exquisitely terse style, when added to the really logical force of his 
argument, must secure him many disciples. Having shown the intimate 
relation which exists between development within the egg and metamorphosis 
external to it, he proceeds to give an idea of the association between genea- 
genesis and metamorphosis, somewhat ui the foUowiug manner : — “ Sup- 
posing that a medusa gives rise to an ovum, and this to a polyp-stalk, which 
has the power of budding, and this in its tiun to a medusa, is not the process 
strictly comparable to the metamorphoses of a caterpfflar ? Thus, a butterfly 
gives rise to an egg, this to a caterpillar, and this eventually to a butterfly. 
All we have to do is to conceive of a caterpillar which has the power of 
producing others by gemmation, and the analogy is strictly correct.” We 
(reviewer), however, are not quite so sure that our author’s analogy is not a 
little too extended, but we do not the less admire the view Av-hich harmonizes 
so many otherwise mcongmous phenomena, and in any case we accept his 
notion of the relationship of development and metamorphosis most readily. 
His book reads more like a fairy romance than a “ plain unvarnished tale ” 
of science. Yet it is commonplace in neither style nor thought, and it is 
a work which, while easily read, requires months for the digestion of its 
contained speculations. 
Dr. Ogilvie, who is so well known as the author of “ The Master-builder’s 
Plan,” has not been so fortunate either in his style or his conclusions as the 
French Zoologist. His treatise displays considerable erudition, but its 
materials are badly arranged, and its style is far from fasciuating. Neverthe- 
less, it merits a careful perusal, for it is evidently the result of deep thought, 
and a careful investigation of the works of others. We have not space at our 
disposal to enter upon all its merits or demerits, but we will just glance at 
the more important conclusions which its author has formulated. Looking 
upon the entire life of an animal as a species of cycle, he divides it into three 
stages. The first, or Proiomorphic, is that in which the animal is not fully 
formed, and refers to the period immediately subsequent to the departure 
from the egg. The second, Orthomorphic, is that in which the definite form 
of the animal has been arrived at, but in which the reproductive organs are as 
yet absent. The third, or Gamomorphic stage, is that iu which the reproduc- 
tive system becomes fully developed. In accordance with these three stages, 
he classifies the alterations of geneagenesis. Thus, those of the Treniatodes 
and mosses, occurring in the first stage, are protomorpMc ; those of the Aphides, 
occurring iu the second stage, are orthomoiphic ; and those of Coelenterata, 
