150 OTTO GLASER. 



crystal, 4 volumes of fairly dense egg-suspension in sea-water +2 

 volumes n CaClc. After two minutes washed in sea-water. 



12.26 insemination moderate. 

 12.28 o fertilization membrane. 

 12.30 I 



12.34 I 



Control normal. All eggs with fertilization membranes in 3—5 

 minutes after insemination. 100 per cent, cleavage. Hundreds 

 of eggs examined in both control and experiment. In Ca-eggs 

 very few divisions. 



In connection with these experiments I noticed that insemi- 

 nation with great excesses of sperm frequently led to results at 

 variance with the above, for fertilization membranes appeared 

 about the majority of the eggs despite the use of Ca, and these 

 eggs developed. This experience strengthened my belief, not 

 only in the validity of the Ca-experiments, but also in the cor- 

 rectness of the original idea, namely that the number of spermato- 

 zoa that come into contact with the egg may make a difference. 



Encouraged by this result, I diluted a sperm-suspension until 

 only the faintest trace of opalescence remained. Several drops 

 of this attenuated fluid were then drawn up into a medicine 

 dropper of medium size and expelled quantitatively. If the 

 dropper, which of course remained infected with sperm, was then 

 used to agitate eggs in a small quantity of sea-water by carefully 

 drawing the water in and expelling it several times, it was found 

 that very soon a few spermatozoa had attached themselves to 

 every egg. In an optical diameter, 4 to 5 sperm could easily 

 be distinguished, but I awaited further changes in vain, despite 

 the fact that the spermatozoa seemed to have reached the eggs, 

 exhibited the usual amount of activity, and were potent in 100 

 per cent, of the cases when applied in larger quantities to eggs 

 of the same lot. The following experiment is illustrative: 



12.17 insemination with infected pipette. 



12.18 o fertilization membranes. 



