STUDIES OF FERTILIZATION 551 



stereoblastula. In the second B fertilization there were a few 

 abnormal prismatic plutei, while the majority were gastru- 

 lae; some stereoblastulae. The third fertilization resulted in 

 extremely abnormal ciliated types. The fourth and fifth did not 

 proceed beyond abnormal cleavage stages. 



The eggs have evidently lost something which affects their 

 power of fertilization. Table 3 shows the measure of loss of the 

 sperm-agglutinating substance, and justifies the general conclusion 

 that this is a factor in the result. The loss of other substances 

 may also combine in the decrease of fertilizing power, but of this 

 we know nothing definite. As a matter of fact, fertilizing power 

 is gradually lost with decrease of fertilizin content of the egg. 



A considerable number of eggs go to pieces during the washings. 

 This was especially noticeable in the A series of the above experi- 

 ment. Thus after the 19th washing my notes record that eggs 

 were stuck to the tube to the 3.5 cc. mark, whereas in B where 

 the eggs were protected by jelly, only a very few stuck and these 

 did not extend above the 1 cc. mark. Such eggs liberate anti- 

 fertilizin, and if this is present in sufficient amount it may conceal 

 the fertilizin production of the intact eggs. This phenomenon 

 appeared a number of times in my earlier experiments when eggs 

 were shaken too strongly in the effort to get rid of the jelly, result- 

 ing in injury to a large proportion of eggs, which soon broke down 

 and neutralized the fertilizin produced by intact eggs. 



One other experiment with apparently much more decisive results 

 may be given (Aug. 18, 1913). In this experiment the shaking lasted 

 45 seconds and over 99 per cent of the eggs were stripped of jelly. The 

 eggs were then precipitated by the centrifuge using just enough force 

 to ensure complete precipitation, and the supernatant fluid poured off. 

 It was very highly colored, showing that many eggs had been broken. 

 It tested to a dilution of 1/12800, giving a 5 second reaction. The 

 eggs were then repeatedly washed about 10/1.5 each time. The time 

 of change and tests of supernatant fluids are shown in table 5, p. 552. 



3:45 P.M. The fluid in 15 now gives a 6 second reaction, showing 

 that some eggs are still producing fertilizin, but that it is rapidly neu- 

 trahzed. 



After the 8th washing these eggs had extremely little capacity for 

 fertihzation, although only 24 hours old: Fertilization 1. 9:08 a.m. 

 August 19: A few drops of stirred up egg suspension put in 9 cc. sea- 

 water and 3 drops 1 per cent sperm added. This is an enormous excess 



