ABSTRACT
In June 1913, a number of large male Luidia were obtained at Plymouth, and to all external appearances the gonads appeared to be perfectly ripe ; when, however, the spermatic fluid in sea-water was examined under the microscope, the spermatozoa were found to be quite motionless, and repeated experiments showed them to be quite incapable of fertilising ripe eggs of the same species. It was found, how-ever, that the addition of a few drops of to a suspension of sperm in sea-water immediately caused active movement. When such “activated “sperm was added to eggs from the same female as before, every egg was quickly fertilised and large numbers of healthy larvæ were obtained from the culture.1
An essentially similar’ phenomenon was observed, this year in the case of several male Asterias glacialis.
This was also observed by R. S. Lillie (2) in the case of the spermatozoa of the frog.
The solution of cerium was not alkaline in solution, being faintly acid to neutral red and phenophthalein.
I understand that Prof. Lillie intends to investigate whether the behaviour of spermatozoa to egg-extractives and to trivalent-positive ions are really identical phenomenon or not ; further discussion of the point must be reserved until absolute certainty is established.
Journ, M. B. A.,’ vol. ix, p. 334,1912.
