170 A. H. K'EGINALD BULI^KR. 



out how the spermatozoa behave toward jelly from other 

 sources thau that from the eggs of the Echinoidea. 



When the oosporangia of Cjstocyra barbata (oue of 

 the Fucaceaj) are liberated iuto sea- water, tlie outer coat 

 vapidly swells and gelatinises. Spermatozoa from Arbacia 

 were added to a preparation containing some of the oospor- 

 angia. At a certain stage in the gelatinisatiou the sperma- 

 tozoa entered the jelly in large numbers, thus becoming 

 densely crowded together in it. 



A similar gathering was observed when the seed-coat of 

 Liuum nsatissimum was placed in water containing 

 spermatozoa. The outer cell-walls rapidly swell and become 

 gelatinous. The spermatozoa, when the jelly had reached a 

 certain consistency, collected in it in large numbers. 



It was also found that if the gelatinous coat of an 

 Echinus egg be separated by shaking, and spermatozoa be 

 allowed access to the coat after several hours' isolation, the 

 number of spermatozoa which will gather in it is very 

 considerable. 



The conclusion that is to be drawn from the above experi- 

 ments appears to be that the spermatozoa are so constructed 

 that they will bore their way into any jelly of a certain 

 consistency without any aid from canals, chemotactic sub- 

 stances, or influences from living protoplasm. 



Massart, as already mentioned, explains the radial pene- 

 tration in the frog by supposing that the spermatozoa seek 

 to pass from the more watery to the less watery layers of 

 jelly, owing to a sensibility to these differences in saturation. 

 Although this theory is plausible, it does not appear to me 

 to be convincing. It does not sufficiently explain why the 

 head of a spermatozoon is at first pushed iuto the jelly in a 

 radial direction. After the head has been pushed in, whether 

 this be radially or somewhat obliquely, the spermatozoon of 

 Echinus usually takes a fairly straight course with respect 

 to the axis of the head. Evidence of picking and choosing 

 between the gelatinous layers thus appears to be wanting. 

 After an egg of Echiuus has been in water for several hours 



