THE OVUM IN THE AMPHIBIA. 225 



which this was employed, could be relied on, it was necessary to confirm the facts 

 ascertained by chemical investigation, by observing the mode of action of solutions of 

 caustic potass, and other chemical agents on the spermatozoa, by means of the micro- 

 scope. As my observations on the effect of chemical agents on the spermatozoa have 

 been confined for the present to those of the Frog, I shall state the results of these 

 observations with the microscope before mentioning the experiments. 



All the observations were made immediately after the spermatozoa employed had 

 been obtained, by the course already mentioned, and not by vivisection from the 

 vesiculse seminales or the testes, sources which are objectionable from the facts shown 

 in Dr. FRERICHS' analyses, that a large quantity of albumen is always found in the 

 immature cells in the testes, with which the spermatozoa, obtained from that source, 

 are constantly mixed, while there is no trace of albumen in the mature spermatozoa. 



1. Solution of Caustic Potass. The solution employed was in the proportion of 

 twenty grains of caustic potass (Potassa fusa) to one ounce of water. This was the 

 solution employed on most occasions in the following experiments, and which quickly 

 and entirely dissolves the spermatozoa. When a drop of semen, in which the sper- 

 matozoa are active and abundant, covered by a pellicle of talc on a plate of glass, is 

 attentively examined, while a very small quantity of the potass solution is applied to 

 the edge of the talc, the act of dissolution is easily witnessed. As the solution spreads 

 beneath the talc the spermatozoa first brought into contact with it are instantly de- 

 stroyed, while the motions of those at a distance become slower and slower, until, when 

 the fluid has nearly approached, they entirely cease. The instant the fluid comes into 

 contact with the spermatozoa, they roll up on a sudden into a spiral form, the change 

 commencing at the apex of the caudal extremity,, and each becomes a rounded mass, 

 which quickly dissolves and disappears in the homogeneous fluid. The action of the 

 potass in this destruction of the spermatozoa, as seen by the microscope, is very similar 

 to, in appearance, and strongly reminds one of the action of fire on the barbs of a feather, 

 which become frizzled in an instant, leaving only a scoria that soon disappears. 



2. Nitrate of Potass. This, as in the preceding case, was in solution in the pro- 

 portion of twenty grains to an ounce of water. It destroys the spermatozoa much 

 less quickly than the caustic potass. When applied, as above, to the edge of the talc, 

 the spermatozoa first become on a sudden motionless, and are in general elongated, 

 and afterwards are very slowly dissolved. 



3. Diluted Acetic Acid. When this is applied to the spermatozoa in the same way 

 as the solution of potass, it quickly destroys all signs of vitality. The movements 

 immediately become slower and very soon entirely cease, and the spermatozoa are 

 extended at full length, and are but rarely folded on themselves, as they usually are 

 in natural death. I could not satisfy myself that the acid has any other effect on 

 them chemically than that of contracting and rendering them smaller. It did not 

 appear to dissolve them. Mr. GULLIVER* has mentioned that the spermatozoa of the 



* Loc. cit. 

 MDCCCLI. 2 G 



