2 DR. RANSOM, ON GASTEROSTEUS LEIURUS. 
tion of the object. ‘They are then seen as circular objects, 
perfectly homogeneous and of moderate refractive power. 
(See Pl. .I Fig. 1.) They are acted upon by water ina remark- 
able manner, varying with the quantity. Thus, if water ap- 
proaches the germinal spots only after having had to traverse 
a portion of the egg, as happens in unbroken eggs, it slowly 
dissolves them, at the same time causing the appearance of 
fine granules in the colloid mass. But if water in abundance 
acts upon the germinal spots contained in escaped germinal 
vesicles, or on the vesicles within very minute ova before 
the food yelk is formed, it causes them to become dark- 
bordered, variously tailed in shape, vacuoles appearing at the 
same time, and does not dissolve them even after very pro- 
longed action. (See Figs. 2 and 3.) At the same time it 
produces a change in their substance or surface, as a result 
of which they. are rendered insoluble in 5 or 10 per cent. 
solutions of alkaline chlorides, although the spots of freshly 
escaped vesicles are rapidly soluble in the same fluids. A 
weaker 1 per cent. solution of chloride of sodium acts like 
water on the germinal spots of freshly escaped vesicles ; but 
after about an hour they resume the round form, and the 
idea is thus suggested that they may be capable of contrac- 
tions like those seen in white blood-corpuscles. 
The disappearance of the germinal spots of vesicles con- 
tained in the larger eggs, when exposed to the action of water, 
appears to be due to the solvent action of the saline or other 
constituents of the yelk carried through by endosmose. 
The germinal spots of recently escaped vesicles when acted. 
on by a 5 per cent. solution of chloride of sodium, flow 
together and fuse into a larger drop, and ultimately the large 
drop gets paler, vacuolates, and vanishes. (See Fig. 4.) I 
conceive the spots to be drops of a thick fluid, having a 
composition different from all the other structural elements 
of the egg, and resembling the other varieties of protoplasm 
only in their extreme instability and liability to vacuolate. 
The vesicular wall was found to be remarkably stable and 
firm; it was dissolved, however, by a weak solution of 
ammonia. Were it not for the resistance afforded by this 
membrane, the disappearance of the germinal spots in the 
osmotic current of water charged with the salts of yelk might 
suggest a plausible explanation of the ultimate disappearance 
of the germinal vesicle and contents, in the ripe ovarian 
ovum. 
I will not prolong this paper by describing in detail the 
yelk of ovarian ova, but only mention that the primitive yelk 
differs in chemical and physical characters from either the — 
‘ 
