Botany and Zoology. 297 
polyp and man, and all organic forms intermediate between these ex 
g 
to the position in the series, We nowhere see plants or animals reac 
maturity in any other pg than by development or growth 
gard e race 
the earliest embryonic condition of each individual ta the last, there is 
a connected series of observ ved changes or differentiations, and no break 
proof, we have no other alternative than to look to the analogies of na- 
ture and the geological record. The direction in which the former 
point is obvious; the testimony of the latter is thus far negative, but is 
it complete enough to be a safe guide 
of the di ficalties met genre in explaining the first introduc- 
simpler or even as simple as the conditions necessary for their repro- 
duction ibe after they have been once created? Preliminary then to 
their first appearance, conditions necessary for their growth en have 
been provided for; for, if, as I belie page were created as , the . 
conditions must have "been'e atime 5 o those in which: the living 
of so if a nada oe. who are known to sola: taste mo: 
first j inhabitants of our globe.”—( Contrib. Nat. Hist. of U. States, i, 12.) 
_ This hypothesis would answer very well for spawning fishes and rep- 
whose eggs may be trusted to the effects of physical agents. But 
does it _ us with regard to viviparous fishes, es, viviparous reptiles, and 
mamm 'o take the case of the mammals, what “conditions con- 
formable. to those in which the living representatives first introduc 
how reproduce themselves” would answer the purpose for the devdaye 
ment of the young, except an uterus, or somet ing analogous to an 
and for its nourishment after birth, except a mammary gland or 
waenne es te to one? And how could the an uterus or a 
Mammary gland without organs of re locomotion, &e.; in 
other words, a — the egg, it essary to 
some kind of a n organism for the egg oF ve in. lf such organism 
Am. Jour. Sc1.—Szconp Series, Vout. XXXVI, No. 107.—Szpr., 1863, 
38 
