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 Lissotriton, 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, was 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 



