130 JACQUES LOEB 



The idea of a negative reaction of the spermatozoa to the egg- 

 sea water is in contradiction to Lillie's statement that the sperma- 

 tozoa are positive to the egg-sea water. The writer is not quite 

 sure whether Lilhe's statement is based on a correct interpreta- 

 tion of his observations. 



Lilhe introduced a drop of Arbacia egg-sea water into a suspen- 

 sion of Arbacia sfperm under a cover glass. In this case a dense 

 ring of spermatozoa was formed "at the margin of the drop with 

 a simultaneous formation of a clear external zone about 1.5 to 2 

 mm. wide; the ring then breaks up into small agglutinated masses 

 and so becomes beaded" (p. 550). In the interior of the drop 

 very few spermatozoa are found. If the spermatozoa were posi- 

 tively chemotropic to the egg-sea water, as Lillie suggests, they 

 should rush into the drop instead of forming a ring around it. The 

 writer is inclined to interpret this formation of a ring with a clear 

 external zone around it as an indication that the spermatozoa are 

 negatively chemotropic to the strong egg-sea water and possibly 

 positively chemotropic to the more diluted egg-sea water or to the 

 dense collection of spermatozoa in the ring. Those in touch with 

 the margin of the drop are repelled by the drop and those at some 

 distance from the drop are attracted towards the ring or towards 

 the drop. This creates the dense ring next to the drop of egg-sea 

 water and explains the formation of the clear space externally to 

 the ring. 



When a cluster scatters it does not scatter equally but one 

 notices that isolated microscopic lumps or beads of spermatozoa 

 may be left in the center of the original cluster. Later these 

 beads or lumps scatter also. It is possible that the spermatozoa 

 constituting these lumps or beads stick temporarily together and 

 that this is caused by a specific substance contained in the egg-sea 

 water. This agglutination, however, cannot account for the fact 

 that cluster formation is only possible if the sperm is very motile. 

 The cluster formation is, aside from the increased motility, the 

 only striking phenomenon which the sperm of the Californian 

 sea urchin shows in the presence of egg-sea water. 



The writer wishes the statements of this paragraph to be taken 

 only provisionally. 



