THE OVUM IN THE AMPHIBIA. 
223 
in suspension had subsided, and only the colouring' matter actually combined with 
the water gave it its red hue. At the end of half an hour I removed the ova from the 
solution to clear water for examination, and then found that the interior of the enve- 
lope was coloured by the water which had entered, but that the greater portion of the 
colouring matter had been arrested and separated at its entrance and adhered to the 
surface. One ovum of Lissotriton palmipes, however, to my great surprise, had a little 
dense mass of colour deposited at one point only of the dark surface of the ovum, not 
merely within the envelope or its chamber, but actually beneath the vitelline mem- 
brane, between it and the yelk, as was distinctly proved by turning the egg on one 
side and viewing it in profile. Not one of the other eggs, placed in the solution, either 
of the Triton or Lusotriton, showed any appearance like this ; so that while I am 
debarred from expressing a decided opinion that the spermatozoon does not enter the 
ovum, I can only regard the appearance mentioned as entirely accidental, and not as 
a normal occurrence ; but as resulting, perhaps, from some minute puncture or other 
accident during the removal of the eggs from the body or the oviduct. 
But in order, if possible, to remove another source of doubt, it seemed necessary to 
make some trial with the colouring material employed by Prevost and Dumas in their 
experiments ; and some further examination of that used in my own ; and to ascertain 
whether any solid particles or granules of matter, held in suspension in ink or in car- 
mine, and equal in size to the spermatozoa of the Frog or the Newt, can be passed 
through the filter, or can be separated from the fluid portion by filtration, like the 
spermatozoa, when precisely the same mode is followed, and the same means and same 
description and number of filter-papers are employed, as in the filtration of the seminal 
fluid. The solution of these questions it was evident must tend to confirm or to 
unsettle the previous conclusions. I first tried ink, and used a part of the identical 
filtering-paper employed to separate the spermatozoa. The ink passed quickly and 
freely through three filters without losing any of its intense black colour, and carried 
with it only a very few extremely minute granules, much smaller in size than the 
spermatozoa of the Frog; so that it seemed fair to conclude that the colour imbibed 
by the ova from ink, in MM. Prevost and Dumas’ experiment, Avas due to the admis- 
sion of the chemically combined colours of the fluid, and not to an admission into 
the texture of the egg-envelopes of solid particles held merely in suspension in the 
fluid. Consequently this experiment seemed to negative the supposition that, from 
the fact of the interior of the egg-covering becoming blackened, solid particles of 
matter, equal in size to the spermatozoa, must have penetrated into the envelope 
during its expansion ; and there seemed less reason to believe that the spermatozoa, — 
bodies very much larger than the ink-granules, — could enter it. Carmine was then 
tried. A solution of this colour could scarcely be made to pass through even a single 
filter. This seemed to be due chiefly to the fact that the greater proportion of the 
colouring matter of the carmine used (the water colour pigment of artists) was com- 
bined with gum and an earthy base, and consequently most of the colour was in 
