ORIGINAL COMMUNICATIONS. 
On the SrructursE and Growtu of the OvaRIAN Ovum in 
GASTEROSTEUS LEIURUS. By W. H. Ransom, M.D. 
(Read at the Meeting of the British Association in Nottingham, 1866.) 
I puRPOSE to speak in this paper of some poimts upon 
which I have been led to adopt conclusions at variance with 
those generally accepted on the mode of growth and structure 
of the early vertebrate ovum, not to discuss the whole ques- 
tion. 
It is remarkable at how early an age the ovaries are found 
to contain perfect young ova. Fry of +” in length, and not 
more than one month old, have well-developed ova in their 
ovaries, and the young males are even more remarkable in 
respect of the early development of the male gland, in which 
actively moving spermatozoids are found when the fry are 
not above 1” in length. 
The germinal vesicle, which is always present in the 
earliest recognisable ova, contains, besides the germinal 
spots, a delicate translucent colloid mass, which, like a pellet 
of thick mucus, supports and gives great resisting power to 
the vesicle. From very various and not clearly ascertained 
causes, a fine molecular deposit, easily dissolved by weak 
solutions of alkaline chlorides, is apt to appear in the colloid 
mass. 
The germinal spots are embedded on the surface only of 
this colloid mass, and lie in contact with the inner surface of 
the vesicular wall. They are very sensitive to the influence 
of the medium in which they are examined, so much so that 
it is extremely difficult to observe them in a perfectly 
unchanged condition. This can be done, however, by using 
the maternal secretions, or by employing only a very small 
amount of water, and using all possible speed in the prepara- 
VOL. VII.—NEW SER. a 
