Dr. Burnett on the Development of Viviparous Aphides. 73 
est physiology who has not learned that widely different teleolog- 
ical significations may be concealed beneath isomorphic animal 
forms. 
appreciation of this whole class of anomalous phenomena under 
iscussion. But we will revert to the subject of Owen’s hy- 
As to the chief point in this hypothesis, the continuation of 
the primary germ-mass as a leaven, from brood to brood, it re- 
quires but little thought to perceive that it is physically impossi- 
le. I would first allude to Owen’s statement, quoted above, that 
& portion of the germ-mass is taken into the abdomen of the em- 
bryo Aphis, and as he thinks, assumes, without any change, the 
Position of the ovarium. By this he refers, undoubtedly, to the 
vitellus-looking mass I have described in my observations, and ac- 
cording to which, also, it appeared to serve only as the nutritive 
material out of which the digestive organs and the germs are form- 
Moreover, I feel quite sure that the germ-cells are new cells 
formed in the abdomen, and not those derived from the parent. 
is clearly evident that this succession must stop with brood B; 
for these residual germ-cells which compose B in its earliest con- 
dition are lost in the developmental processes, and the germs of 
individuals C, which are found in B, are, each, primarily, nuclea- 
ted cells formed de novo, as I have observed and above described. 
With these observed’ conditions of development, it is impossible 
for the individuals of the successive broods to inherit the original 
‘permatic force in the continuation of the original cells. 
_ The hypothesis of Owen, therefore, plausible and ingenious as 
it may seem, does not appear to me to accord either with observ- 
ed facts, or with the soundest physiology of the reproductive pro- 
cesses. I may here remark also, that his doctrine of Partheno- 
8ensis, based as it is upon the conditions of the hypothesis in 
destion, cannot, as such, be sustained, for the same reasons, an 
&. its phenomena would a pear to find their solution either in 
Steenstrup’s doctrine of “ Alternation of Generations,” so-called, 
or In the conditions of true gemmiparity—admitting, provision- 
ally, that Steenstrup’s doctrine, and gemmiparity, include really 
different: physiological conditions. 
“ut the most important explanation advanced, and the last 
Which [ shall notice, is that offered by Steenstrup* in his doctrine 
ington, the Al i i the Pro ion and development of An- 
fea ries Sortie oe en erga tte 
of Animals. Transl. by the Ray Society, London. 1845—passim. 
Stooxp Suuins, Vol. XV, No, 49—Jan, 1854, 
