Ova of the Salmonidw. 223 



Fahr., the coagulation took place pretty rapidly ; at 120°, 

 more slowly ; and slower still at lower temperatures ; at 

 100°, the time required for coagulation to take place was 

 about half an hour. The higher the temperature at which 

 the coagulation was effected, the greater was the firmness of 

 the coagulum ; at the boiling temperature, continued for a 

 few minutes, it was as firm nearly as the yoke of the egg of 

 the common fowl similarly treated. That, in all these in- 

 stances, water penetrated and mixed with the vitellus can 

 hardly be doubted ; at 100°, it may be mentioned in confir- 

 mation, that the coagulation extended gradually, spreading 

 almost from a point. These trials were made with unim- 

 pregnated eggs. Repeated on others that had been subjected 

 to the influence of the spermatic fluid by admixture about 

 thirty-six hours previously, the effect of coagulation was 

 decidedly slower in taking place, i. e., the fluid resisted longer 

 incipient coagulation ; but when it commenced, it seemed to 

 proceed as rapidly in one instance as in the other. 



Thirdly, Of the action of alkalies and salts. — Ammonia or 

 potassa, or the sesquicarbonate of either alkali, in solution, 

 added in very minute quantity to the fluid vitellus, did not pre- 

 vent its coagulation ; but, if of moderate strength, no obvious 

 effect was produced, either at the instant of admixture or 

 afterwards ; moreover, if coagulated vitellus, obtained by 

 the action of water, was added, a certain portion of it was 

 dissolved. r0 ° 



Common salt, muriate of lime, muriate of ammonia, mu- 

 riate of barytes, nitre, phosphate of soda, sulphate of magnesia, 

 alum, acetate of lead, in solution, acted very similarly ; when 

 weak not preventing coagulation, but preventing it when 

 not much diluted. In the instance of common salt, a solu- 

 tion so weak as to be of the specific gravity 10,045 to water 

 as 10,000, on addition to the vitellus, did not impair its 

 fluidity ; it required to be reduced to the specific gravity 

 10,029 to effect coagulation. The stronger saline solutions, 

 in the same manner as the alkaline, were found capable of 

 dissolving a certain quantity of the coagulated vitellus. 



Fourthly, Of the action of acids and some other agents. — 

 The fluid of the vitellus was not coagulated by the tartaric, 



Q2 



