2'SQ Sfifflirs in the Phi/siolof/i/ of Fertilization 



III Exjis. 1, 4 and 5 the tempenitures of the water at thu moments 

 of fertilization are recorded. Table V shows that the maximum varia- 

 tion is only 1 C, and as there is no rise and fall correlated with the 

 rise and fall of the fertilization percentages, there can be no connection 

 between the two. 



The conclusion can thus be drawn ft'om the experiments that lying 



in water increases the self-fertilizing capacity of eggs and sperm. This 



increase continues up to a maximum, after which it falls off again, 



, probably due to the loss of both self- and cross-fertilizing power by the 



sperm. 



Although it is certain that there is an increase in the extent to 

 which self-fertilization takes place after the eggs and sperm have been 

 for some time in sea-water, yet the experiments do not decide whether 

 it is due to a change in the eggs or in the sperm. It was thought that 

 further experiments to decide this point could be made as follows : 



About half the eggs contained in the oviduct are removed and 

 placed in sea-water. The hole in the oviduct wall through which the 

 eggs were removed is then clipped and the sperm removed from the 

 sperm duct to make up a suspension. At regular intervals equal 

 amounts of this sperm-suspension are used to fertilize (1) some of the 

 eggs already lying in water, and (2) some more eggs, just removed from 

 the oviduct. If the eggs (1) showed the typical rise and fiill in self- 

 fertilization percentages, while the eggs (2) did not, the phenomenon 

 would be due, at any rate in part, to an alteration in the eggs during 

 their stay in sea-water. 



The experiment was trietl and was a comjjlete failure. The eggs 

 which had been for varying lengths of time in sea-water showed the 

 usual increase and decrease in fertilization percentages, but the propor- 

 tions in eggs taken from the oviduct immediately before each fertilization 

 were quite irregular. The reason for this will be apparent when the 

 results of experiments to be described below are seen; for it will be 

 shown that eggs and sperm taken from different parts of the genital 

 ducts of a given animal behave quite differently in their capacity for 

 self-fertilization. Now, whereas the eggs lying in water are thoroughl}' 

 mixed together before being used, and are thus homogeneous material, 

 every time that eggs are removed from the oviduct for comparison, 

 a sample is obtained having a ijuite different behaviour. 



The reverse experiment, namely that of removing all the eggs and 

 half of the sperm from an animal and then taking samples of the 

 remainder of the sperm from the vas deferens at each fertilization, is 



