242 



FRANK R. LILLIE. 



Table III. 



not fertilize at all. It should of course be noted that the sperm 

 suspensions used were diluted 300 times in the actual insemination 

 (10 c.c. = 300 drops of sea-water, and one drop sperm added). 



Thus time is an important factor in the fertilizing power of 

 sperm dilutions from 1/4 per cent. down. The matter cannot 

 be stated with great accuracy, but we can say in general (referring 

 to Table II.) that sperm suspensions from 1/300 per cent, to 

 1/1200 per cent, lose their fertilizing power nearly completely in 64 

 minutes; from 1/2400 to 1/24,000 in 32 minutes; from 1/30,000 

 to 1/60,000 in 16 minutes; from 1/120,000 to 1/240,000 in 6 

 minutes. Table III. shows loss of fertilizing power of higher 

 concentrations by a different method. 



C. We are now in a position to understand the principal reason 

 why the curves of successive half or quarter dilutions of a i 

 per cent, sperm suspension run off so rapidly. The reason is 

 that the preparation of the series requires time, 10 to 20 or more 

 minutes. In the early experiments of this kind the significance 

 of brief periods of time was not recognized, and so no time records 

 were kept; but I have 13 curves with accurate time records. 

 Of these I reproduce only two (Fig. 4). For this experiment 

 (Sept. 5), (i) 6.6 c.c. of I per cent, sperm was prepared, 9.30 

 A.M. (2) 4 c.c. of I was transferred to a Syracuse watch crystal 

 and 4 c.c. of sea-water added (= }4, per cent.). (3) 4 c.c. of 2 

 was transferred to crystal 3 and 4 c.c. sea-water added (= 3<£ 

 per cent.) and this was continued to 12 numbers (finished at 

 9.39.30 A.M.). The suspensions 2-12 was then divided in two 

 equal amounts of 2 c.c. each, making series A and B. To each 

 crystal of series A 2 drops of a i per cent, egg-suspension were 



