40 QUATREFAGES, ON THE METAMORPHOSES 
Salpz could only produce chain-salpz, and only by gemma- 
tion, whilst the chain-salpze produced isolated Salpz, and 
only by ova. The discovery of the now well-known life- 
history of the Medusze marks the next era. Saars and Sie- 
bold showed that the Medusa aurita deposits an egg, which, 
when fructified, gives rise to a polyp, which grows by gem- 
mation, and by fissuration produces from a single individual 
numerous small Medusz, who, again, in their turn, produce 
ova. Other phenomena were soon collated with these, the 
fissiparous generation of Annelida, and the various pro- 
cesses exhibited by certain Hydrozoa, Infusoria, and Spon- 
vide. The remarkable larve of the Hchinodermata, from 
whose viscera the future perfect beimg is given off by a pro- 
cess of gemmation, were described by T. Miller in 1845, 
and the researches of Kuchenmeister and Van Beneden, after- 
wards illustrated the remarkable migrations and metamor- 
phoses of the Helminthes. <A great portion of M. de Quatre- 
fages’ volume is devoted to the details of these researches ; 
the history of the gradual establishment of the facts at pre- 
sent known with regard to what he calls geneagenetic 
phenomena, being ably treated. And now it may be 
asked, what are our author’s general views with regard to 
these phenomena? After passing in review the various 
theories brought forward in explanation, from the time of 
Chamisso, criticising more particularly those of Steenstrup 
and Owen, he states that the opinions which he himself had 
formed on this matter, agree almost entirely with the views 
expressed by our eminent countryman Dr. Carpenter, in the 
‘Medico-Chirurgical Review,’ 1848, views which we believe 
are held by most of the advanced school of English biolo- 
gists. Oviparity must not be considered as a process homo- 
logous with genuine parity; the one is the result of sexual 
union, and is of a nature peculiar to itself; the other is 
simply part of the process of growth, comparable only to the 
growth of a mutilated limb. The gemmation of the 
Hydra, the medusification of the Strobila, the virginal par- 
turition of the Aphis, the segmentation of the Nais, the 
gradual development of the Echinoderm, within its Plutean 
Jarva, and, similar instances, are all mere phenomena of 
growth, whilst sexual reproduction js a distinct process, des- 
tined only to occur when the former fails. Hence we con- 
sider, as do M. de Quatrefages and Dr. Carpenter, that the 
term " parthenogenesis i 1S inapplicable to any of the phenomena 
mentioned, inasmuch as it is likely to mislead, and appears 
to imply some connection between these phenomena and the 
female organs of generation. 
