1907.] Torelle, Fertilisation of Eggs of Asterias and Arhacia. 113 
In the ammonium chloride sohitions of .1% and .5%, the 
activity of the spermatozoa is increased ; but they continue active 
for some hours, only in the .01 % solution. 
Active and inactive sperm of Arbacia is affected by the solu- 
tions named above, in essentially the same' way as is that of 
Asterias, with the difference that Arbacia sperm does not become 
active so readily. 
During August and September, 1903, at the Marine Biological 
Laboratory, in Woods Hall, Mass., a series of experiments were 
carried out on the eggs of Asterias forbesii and Arbacia punctu- 
lata, with the object of discovering if spermatozoa normally 
ineffective in fertilization, could be rendered effective by immer- 
sion in the solutions named above, and also to see if changes 
brought about in active spermatozoa by an immersion in such 
solutions, would affect the development of the egg. In this paper 
no account will be given of the results as seen in sections of the 
eggs ; these will be given in a later paper. 
In the care of eggs' and sperm, and in the manipulation of 
instruments and dishes, the usual precautions to prevent contam- 
ination, were taken. The eggs to be fertilized were placed in 
small glass crystals, or in finger-bowls, with an ample amount of 
sea-water. The spermatozoa, after immersion, were added to the 
eggs by means of a pipette, at intervals of one, five, ten and fifteen 
minutes, and, in some experiments, after an immersion of twenty 
and thirty minutes. The eggs so fertilized were compared with 
eggs normally fertilized and kept as a control. In each experi- 
ment, the condition of the spermatozoa before immersion was 
observed ; the effect of immersion for shorter or longer periods 
' of time in the various solutions used ; the per cent of eggs which 
divided after fertilization by the spermatozoa which had been 
immersed ; and, in most cases, the development of the eggs was 
watched for two days or more. 
It was observed that spermatozoa, rendered inactive by being 
placed in certain of the stronger solutions, recovered their activity 
to some extent on being replaced in sea-water.* It is, therefore, 
*See Table II. Exper. b. 
