EXPLOSION OF SPERMATOZOA OF LOPHOPANOPEUS BELLUS. 293 



change in the normal appearance of the spermatozoa, thereby 

 pointing to the second factor, namely, osmotic pressure, as the 

 one which undoubtedly operates in bringing about the eversion 

 of the vesicles. 



10. Ovarian Fluid. Since a reduction in osmotic pressure 

 produces the explosion of the spermatozoa, the next question 

 which naturally arises is whether the female gonacls at the time 

 of fertilization produce a hypotonic substance which, when com- 

 ing in contact with the spermatozoa, causes them to explode, 

 thereby bringing about fertilization of the ova. In order to 

 test this out, the ovaries and oviducts were mashed up in sea 

 water and the living spermatozoa were then surrounded by this 

 mixture. In some cases (not all), a few of the spermatozoa 

 exploded violently. The nuclear cup at first swelled and became 

 homogeneous (Fig. 34). Then the vesicles were everted with 

 considerable force and in many instances, the primary vesicle, 

 or both the primary and secondary vesicles completely disin- 

 tegrated, leaving stages like those shown in Figs. 35-39. Whether 

 this was due to some agent produced by the female gonads or to 

 some other agent cannot be definitely stated, for not all of the 

 spermatozoa were affected in the same manner as those mentioned 

 above. However, it is also significant that the ovaries used 

 during the months of the year when the investigations were 

 conducted (June and July), were past maturity. They were 

 small and immature and this might account for the results 

 obtained. Another significant fact to be taken into consideration 

 is that in control experiments in which living spermatozoa from 

 the same males as those used in the experiments with the ovarian 

 fluids, were surrounded w r ith sea water alone, none of the sperma- 

 tozoa exploded. Now, the question arises, why should we get 

 a violent explosion of even a few spermatozoa when ovarian 

 contents are used and no explosion when the ovarian fluids are 

 lacking? I am strongly of the opinion that the female gonads 

 produce some substance which is responsible for the explosion. 

 Also, it seems very probable that at the time of sexual maturity 

 of the female this specific substance must be present in such 

 quantities as to activate all of the living spermatozoa. 



11. Acidulated Sea Water. In all cases weak dilutions of the 



