NOTICES OF SERIALS. 
217 
of the new individual is not preceded by the phenomena of segmentation, as also 
is the case with all true eggs. Therefore, their primitive formation, their develop¬ 
ment, and the preparatory changes they undergo for the evolution of the new indi- 
vidual, are all different from those of real ova. Another point is, these viviparous 
individuals have no proper ovaries and oviducts. Distinct organs of this kind I 
have never been able to make out. The germs are situated in moniliform rows, 
like the successive joints of confervoid plants, and are not enclosed in a special 
tube. These rows of germs commence, each, by a single germ-mass which sprouts 
from the inner surface of the animal, and which increases in length and in the 
number of its component parts from the successive formation of new germs by a 
constriction-process, as already mentioned. Moreover, these rows of germs, which, 
at one period, closely resemble in general form the ovaries of some true insects, are 
not continuous with any uterine or other female organ, and, therefore, do not at 
all communicate directly with the external world. On the other hand, they are 
' simply attached to the inner surface of the animal, and their component germs are 
detached into the abdominal cavity as fast as they are developed, and then escape 
outwards through a porus genitalis , exactly as is the case with the eggs of fishes. 
Here, then, comes the important question—What interpretation shall we put upon 
these reproductive parts—these moniliform rows of germs? Ignoring all existing 
special theories relating to reproduction, the observing physiologist would be left no 
alternative but to regard them as buds, true gemmae, which sprout from the inner 
surface of the Aphis, exactly like the buds from the external skin of a Polype.” 
Dr. Burnett then gives the results at which other famous naturalists have arrived 
upon this subject, and a discussion of the relations of the important conclusion at 
which he has alone arrived; and now—“ The final question is, what is the le¬ 
gitimate interpretation to be put upon the reproductive phenomena of the Aphides 
we have described? My answer to this has been anticipated in the foregoing re¬ 
marks. I regard the whole as constituting only a rather anomalous form of gem- 
miparity. As already shown, the viviparous Aphides are sexless; they are not 
females, for they have no proper female organs—no ovaries and oviducts. These 
viviparous individuals, therefore, are simply gemmiparous, and the budding is here 
internal instead of external as in the Polyps and Acalephs ; it, moreover, takes on 
some of the morphological pecularities of oviparity; but all these dissimilar condi¬ 
tions are ceconomical and extrinsic, and do not touch the intrinsic nature of the 
processes concerned therein. Viewed in this way, the different broods of Aphides 
cannot be said to constitute as many true generations, any more than the different 
branches of a tree can be said to constitute as many trees ; on the other hand, the 
whole suit from the first to the last constitute but a single true generation. I would 
insist upon this point as illustrative of the distinction to be drawn between sexual 
and gemmiparous reproduction. Morphologically, they have, it is true, many points 
of close resemblance; but there is a grand physiological difference, the true percep¬ 
tion of which is deeply connected with our highest appreciation of individual ani¬ 
mal life. A true generation must be regarded as resulting only from the conjuga¬ 
tion of two opposite sexes—from a sexual process in which the potential representa¬ 
tions of two individuals are united for the elimination of one germ. This germ- 
power may be extended by gemmation or by fission ; but it can be formed only by 
the act of generation ; and its play of extension and prolongation by budding , or by 
division, must always be within a certain cycle, and this cycle is recommenced by 
YOL. I. Q 
