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398 Reviews and Records in Anatomy and Physiology. 
The announcement of the presence of such a structure on the 
ovum is indeed wonderful, and more especally so since other ob- 
servers, whose attention has been particularly directed to the 
embryological study of these animals, have failed to notice it, 
although one would suppose that an apparatus of this kind must 
be very visible. Keber affirms that he has observed a like struc- 
ture in the ova of some other animals which he has examined. 
But, however well fortified he has sought to make his observa- 
tions, they certainly need more than the usual confirmation, and 
we cannot but regard it as far from being a settled fact in embry- 
ology, that the ovum has a direct structural communication exter- 
nally for the ingress of spermatic particles to its interior. 
After all this discussion of facts, we revert to the primary ques- 
tion, what is the nature of the fecundating act? We have seen 
that its physical phenomena consist in the contact of active vital 
spermatic particles with the mature ovum; that this mature ovum, 
thus affected, experiences peculiar changes which terminate finally 
in the evolution of a new being possessing the characteristics of 
the male as well as of the female parent. It is true that, as was 
observed by Prevost and Dumas, and as has since been confirmed 
by Barry, Newport, and others, the spermatic particles may force 
their way through the envelopes of the egg some distance into its 
interior, but we regard this as an unessential condition of the 
fecundatory act; adhering by their heads to the envelopes of the 
egg, the incessant action of the tails of these bodies would obvi- 
ously tend to force them inwards, and especially through such 
homogeneous, soft tissues as the egg-envelopes. 
As a point of some importance in this connection, it may be 
mentioned, that there are cases where’this intrusion of the sper- 
matic particle into the interior of the ovum does not seem avail- 
able from the very structure of the particle. Thus, with the Deca- 
pod Crustacea, these bodies consist each of a central nucleus to 
which are attached many long radiating processes ; moreover, in 
these animals, the motion of the spermatic particles ceases SO 
shortly after their escape from the body, that this entrance into 
the ovum would not be likely to be effected with even the most 
favorable perforating structure. It may also be here mentioned, 
that as motion is, with these particles, the only visible exponent of 
their vitality, it is highly probable that in these very same anl- 
mals, the merest contact suffices to fecundate the ovum. 
Even admitting the hypothesis of Keber and others, that the 
rmatic particlé is mixed de ipso with the contents of the ovum, 
it would explain nothing, and would approximate us not in the 
least to the nature of this process, for it is just as comprehensible 
that the spermatic particle should fecundate by mere contact, as 
that it should by a material mixing or even an interpenetration 
of its constituents with those of the ovum. So ,. 
