AND ON THE DIRECT AGENCY OF THE SPERMATOZOON. 
289 
tion into the envelopes of the eggs, whether such admixture be made with the bodies 
themselves, or with the water in which the eggs are immersed before they are sup- 
plied to it. 
The question proposed in these experiments by trituration we may now look upon 
as to some extent, if not entirely, answered ; as it seems that although the spermatozoon 
be broken down mechanically before any chemical change can be supposed to have 
taken place in it, — indeed, at the very time it is giving evidence of its vitality, — and 
its organic substance so broken down be quickly afterwards brought into contact with 
the egg in water, at the moment when the egg is most susceptible of its influence, yet 
that no fecundation is then effected by it. It may be urged, it is true, that there was 
no direct proof that the spermatic substance was actually conveyed to the yelk by, 
or with, the water in these trials ; but there was one circumstance which gave fair 
reason to believe that it really was so conveyed. The yelks of some of the eggs 
became much contracted, and, as it were, shrivelled, as when affected by potass solu- 
tion ; of the penetration of which to the yelk there is absolute proof in the decomposi- 
tion of the egg which quickly succeeds to its introduction. It has also been shown 
in a preceding experiment (p. 241) that the yelk becomes similarly affected when 
decomposing spermatic fluid is applied to it. 
The conclusion then which seems to me to be deducible from these investigations 
is, that fecundation is not simply the result of a mere fusion or chemical admixture of 
the substance of the spermatozoon with that of the egg; although such fusion, 
probably, is necessary to the production of the organized body of the embryo, in 
determining its structural and psychical peculiarities, and its definite species ; and 
more or less of which may, possibly, help to determine the sex, and the extent to 
which the structural and psychical peculiarities of the male parent are transmitted 
to the offspring. That this fusion of some portion of the spermatic substance with 
the egg does actually take place, either when the spermatozoon has arrived at, and 
become imbedded in the vitelline membrane, as in the Frog; or, as stated by a 
recent observer*, to occur in the Ascaris Mystax, when it is in immediate contact 
with the yelk itself, is probable, from the considerations now adduced. These views 
are countenanced by the now established fact that the spermatozoon of the Frog, and 
probably also of other Vertebrata, does not fertilize the egg either when it is perfectly 
motionless, — whether from actual death, or from suspension of vitality by narcotiza- 
tion; nor even, as we now find, though living, while simply in contact with the 
surface ; nor until after it has actually passed into the envelopes, and arrived at the 
immediate vicinity of the yelk, — facts which seem, I think, inferentially, to show a 
probability that, whatever conjugation of materials may be effected, some vitalizing 
dynamic influence is also expended by the spermatozoon on the contents of the yelk in 
the production of its changes, — phenomena which have not been found to take place 
* Dr. Nelson, “ On the Reproduction of the Ascaris Mystax” Proceedings of the Royal Society, vol. vi. 
p. 86. Philosophical Transactions, 1852. 
