472 
DR. W. H. RANSOM ON THE OVUM OE OSSEOUS EISHES. 
five minutes, but were languid. Cleavage began six hours after impregnation, the 
masses being arranged irregularly and without symmetry. 
Another mode is thus suggested by which monsters may be formed. Some of these 
ova were left in the chamber at 102° F. for 50 minutes. They became opalescent, their 
inner sacs ruptured and shrunk up. 
Experiment f . — Ova one hour after impregnation were warmed in a cell, upon a 
metal plate, the thermometer resting upon which stood at 103°-104°F. In 2 4 minutes 
they began to be opalescent, and in four minutes they were opake ; the yelk-ball was 
round and filled the yelk-sac, and the inner sac was not ruptured. The opaque yelk 
not being coagulated, diffused in water, on cutting an egg through. In this mode of 
applying the heat, the eggs approached more nearly the temperature indicated by the 
thermometer. 
Experiment g . — Ova 14 hour after impregnation, put for 5 minutes in a chamber at 
90° F., had their yelk-balls globular, relaxed, so as to fill the yelk-sac, and their oil scattered 
and displaced towards the periphery ; but were not at all opaque. Being then replaced 
in the chamber, warmed to 103° F., they soon became faintly opalescent to the naked 
eye, and when examined with a power of X 75 the yelk-balls w’ere found to fill the yelk- 
sac ; even the germinal mass was diffused and the oil scattered in small drops, but no 
coagulation was visible. These eggs were gradually cooled to 58° F., and soon contracted 
so as to form a breathing-chamber ; no contractile waves appeared, but the germinal disk 
concentrated. They were again put, but only for a few minutes, into the chamber 
heated to 109° F., when again the yelk-balls became globular, and effaced the breathing- 
chamber ; again, as they cooled, they contracted so as to cause its reappearance. Once 
more they were put into the chamber at 110° F., when a faint increase of opacity was 
visible, and being removed to the metal plate, at 103° F. they all shortly became opaque. 
In this experiment, I have no doubt that the thermometer in the chamber indicated a 
temperature considerably higher than that reached by the eggs. 
Although the difficulties which stand in the way of warming the yelks to a given 
temperature, and maintaining them there, were not satisfactorily overcome in these ex- 
periments, it is, I think, fair to infer that a moderately elevated temperature quickens 
the yelk contractions, and hastens the commencement of cleavage. It is probable that 
7 5° F. is somewhere about the upward limit of this temperature. 
A higher temperature, which begins probably about 80° F., arrests the contractions, 
and relaxes the yelk-ball, which on cooling recovers itself, unless the heat has been 
carried too far. This limit was not made out with certainty, but is probably about 
100° F. Imperfect coagulation of some of the contents of the yelk, or at least a granular 
precipitation, occurs at about 103° F. 
d. Oxygen and carbonic acid . — The question which I have attempted to answer is 
this ; Is oxygen in the surrounding medium a necessary condition of yelk-contraction 
and of cleavage X 
Control experiment 1. — Ova five minutes after impregnation were placed, in a large 
