234 Papers from the Marine Biological Laboratory at Tortugas. 



fact that in nearly every case examined they have also been found in the 

 uterus along with the apyrene spermatozoa, it must take a long time for 

 them to move into the seminal receptacle. In the uterus a separation of 

 the two kinds of spermatozoa occurs, the eupyrene being retained in good 

 condition while the apyrene may be seen in all conditions of katabolic 

 changes leading to the total exhaustion of the secreted bodies. It may be 

 that the apyrene spermatozoa serve to nourish the eupyrene until the latter 

 are stored in the seminal receptacle, where they may obtain an adequate 

 and independent food supply. Whether this is so or not, it is believed that 

 the apyrene spermatozoa of Stromhus subserve their purpose in the uterus 

 and possibly also in the vagina and bursa seminalis immediately after copu- 

 lation and that their function is connected with their breaking down. 



There are two other ways of explaining the behavior of the apyrene 

 spermatozoa after copulation has taken place. The first of these was 

 suggested to the writer by Professor Conklin and is to the effect that the 

 apyrene spermatozoa in breaking down may liberate a substance which 

 stimulates the eupyrene spermatozoa or the eggs or both during fertilization. 

 The possibility of their being an aid in the final disposition of the eupyrene 

 spermatozoa was indicated by a series of experiments recently performed by 

 the writer.^ It may be that the substance liberated by the apyrene sper- 

 matozoa as a result of the changes which they undergo causes the eupyrene 

 spermatozoa to withdraw from them and eventually to enter the seminal 

 receptacle. 



The fact that the apyrene spermatozoa of Stromhus break down after 

 copulation and are discarded, while the eupyrene are retained and kept in a 

 healthy condition, together with the results obtained by Kuschakewitsch 

 ('lo) in his study of the fertilization of the eggs in Aporrhais pes pelicani 

 these facts, in the writer's opinion, preclude the view that the atypical 

 spermatozoa may participate as such in the fertilization of the egg. 



' While at the Tortugas Laboratory during June 1913, cultures of the contents of the sperm-duct of 

 Strombus gigas were kept alive and observed under varying conditions. The spermatozoa lived longest in 

 cultures made from sterilized sea-water, in some cases as long as 72 hours. The length of life of the sper- 

 matozoa apparently depended upon the extent to which the cultures had been kept free from bacterial infection. 

 In such cultures, there was always a separation of the two kinds of spermatozoa, the eupyrene remaining active 

 for a long time after the apyrene had ceased their movements. In very many instances a clear drop of some 

 substance could be seen attached to the side of an apyrene spermatozoon whose contents had partially or com- 

 pletely broken down. Very striking results were obtained in a few cultures in which a small piece of decaying 

 tissue was included in order to test the reaction of the two kinds of spermatozoa to COi. In every case the 

 eupyrene spermatozoa moved further and further away from the source of the CO2 until they reached the edges 

 of the cover glass. The apyrene spermatozoa, on the other hand, were not greatly stimulated except in one 

 instance, where they gave a distinct, positive reaction, gathering around the pieces of decaying tissue. One 

 effect of CO2 upon the apyrene spermatozoa was to cause a comparatively rapid and complete breakdown of 

 their contents. Unfortunately, for lack of time, these experiments could not be repeated under conditions of 

 greater accuracy. 



