i6o T. H. Morgan. 



per cent, caused the spermatozoa to show some movement 

 in the course of 15 minutes. Alcohol gave better results. A 

 10 and a 6 per cent, solution awakened the spermatozoa to ac- 

 tivity; a 4 per cent, gave the best results of all. In no case, how- 

 ever, was the activity very great. No movements were detected 

 in ammonia-solutions, but only two strengths were used. 



These scattering and incomplete observations show that these 

 substances are in all probability general stimulants for protoplas- 

 mic activity of certain kinds. * 



I have also made a few experiments with the spermatozoa 

 of mice. The spermatozoa were taken directly from the testis 

 of a mouse that had just been killed. The solutions were added 

 to a drop of the sperm squeezed out from the testis into a drop 

 of physiological salt-solution, consequently the dilution is greater 

 than actually given by the percentage. In certain strengths of 

 ether (5 per cent.) and of alcohol (8 per cent.) it appeared that 

 the movement was increased; with ammonia I did not get satis- 

 factory results. The observations are made more uncertain here 

 because, when the testes are opened, spermatozoa in all stages 

 of development are found, and are consequently acted upon dif- 

 ferently by the solutions. It would be more satisfactory to use 

 a larger animal and take the spermatozoa from the vasa deferentia, 

 where they arc all fully formed. It is certain, however, that al- 

 cohol and ether do not produce as great effects on these sperma- 

 tozoa as they do on the spermatozoa of the ascidians and of 

 some other marine animals that I have examined. 



In one of the preparations of the mouse testis the water began 

 to run out at one side and it became apparent at once that the 

 spermatozoa all turned and headed up-stream. It has been re- 

 corded by Kraft that spermatozoa swim in the opposite direction 

 to that in which the cilia of the oviducts act. My observation 

 suggests that movement in this direction is not due to the sper- 

 matozoa swimming against the direction of the greatest action 

 of the cilia, but against the stream that is produced by the cilia. 

 The movement may be a simple physical phenomenon — the lighter 

 tails of the spermatozoa being swept backwards by the current 

 so that the heads are turned up-stream, and the contraction of 

 the tail then causes the spermatozoon to travel in this direction. 



