DB. W. H. HANSOM 03ST THE OVUM OE OSSEOUS FISHES. 
447 
the deepest tinge in their yelk-mass, especially those most exposed to the fluid. Those 
larger eggs which had a food-yelk showed less colour ; what stain had taken place was 
limited to the formative yelk, but many of these yelks were not dyed at all ; the food- 
yelk flowed out from a rupture as a colourless fluid, or changed chemically into a mass 
of clear, starch-like corpuscles. The whole primitive yelk, when dyed, was deformed, 
rendered opaque, vacuolating, and granular, a physical condition favourable for reflecting 
its colour, but unfavourable for exhibiting its true structure or characters. The ger- 
minal vesicle and spots were obscured or quite undistinguishable. 
To test the action of this dye-fluid on the germinal vesicle and contents, I prepared a 
piece of ovary in a 1 per cent, solution of chloride of sodium, as a neutral solution ; then 
bringing into view a free germinal vesicle, I gradually added the carmine solution ; 
slowly the vesicle swelled out, the spots became pale and vanished, the vesicular wall 
seeming to shrivel up. 
That this was due to the ammonia was shown afterwards by repeating the experiment, 
using a dilute solution of ammonia (about 1^ per cent, of Liquor Ammonise) ; the ger- 
minal spots vanished as in the dye-solution, and the vesicular wall also, but an hour 
later. 
Thus it may be said, I think, that whatever value we may attach to this process of 
dyeing tissues, we must not neglect the consideration of the changes which may be pro- 
duced in these sensitive states of matter by the menstrua employed. If the strong, 
tough, and very distinctly solid wall of the vesicle may vanish, if the highly refractive, 
striking-looking spots may be rapidly dissolved by Beale’s carmine solution, who can 
tell what changes it may produce in the almost equally unstable and sensitive substances 
which constitute the growing parts of tissues, and probably even the functionally active 
parts 1 It certainly seems necessary to supplement this method by others capable of 
determining the appearances presented in perfectly indifferent media. 
The yelk-sac took the dye freely ; considering its thinness and translucency perhaps 
as much so as the formative yelk ; the dye was deepest in the thickest sacs. When an 
egg was crushed by strong pressure, so as to reduce the layer of yelk-substance to the 
same thickness as the yelk-sac, the colour was seen to be quite as deep in the buttons 
on this latter as in the formative yelk, but of a somewhat more yellowish red. 
The dyeing is independent of any acid reaction of the substance dyed, as macerated 
yelk-sacs, which had become alkaline from decomposition, took the dye freely. This 
independence of the acid reaction is also further seen by the fact that the acid fqodwelk 
does not take the colour at all. 
The fine structure of the yelk-sac is rendered less distinct by this method, partly in 
consequence of the action of the glycerine, partly from the action of the acetic acid. 
Ammonia does not impair the distinctness of this structure, although it makes the sac 
very clear. 
It will perhaps not be entirely out of place to introduce here the following 
3 p 
MDCCCLXVII. 
