BEHAVIOR OF LOWER INVERTEBRATES 389 



Spent females had little influence, on the sperm discharge of 

 the males, but water which had contained an egg-bearing female 

 would quickly provoke discharge of the sperm. The substance 

 inducing the discharge of the sperm is quite labile as it is de- 

 stroyed by heat or by standing a few days in sea water. 



Lillie (31) has made a study of the behavior of the sperma- 

 tozoa of Nereis and Arbacia. The sperm cells of Nereis are 

 positively chemotactic to weak solutions of C0 2 and various 

 other acids, but they show no response to alkalis. ' In contact 

 with any solid object Nereis spermatozoa tend to carry out 

 circus movements in an anti -clockwise direction, when fresh, 

 but soon come to rest." They are especially attracted by sub- 

 stances given off by the eggs. The same is true for the sperm 

 of Arbacia, whose general behavior resembles that of the sperm 

 of Nereis. Chemotaxis to egg substances is probably an im- 

 portant factor in bringing about the fertilization of the egg. 



MacCurdy (32) has shown that Asterias forbesi is negatively 

 phototactic. He finds that light produces chemical changes in 

 the starfish which were studied by examining the sea water 

 containing specimens exposed to the light. 



Metalnikow (33) finds that Paramoecia which at first ingested 

 injurious substances came after a few hours to reject them. 

 In another communication (34) experiments are reported on 

 feeding infusoria with sepia and carmine. At first both sepia 

 and carmine were ingested; after a few days the carmine was 

 ingested in very small quantities, but the sepia was engulfed 

 in considerable quantity. 



Moore (35) finds that Diaptomus bakeri ordinarily indifferent 

 to daylight becomes negative upon the addition of small amounts 

 of caffein, strychnin, and atropin, while acids, alcohol and ether 

 evoke a positive response. 



Morse (36), who has made a detailed study of the habits of 

 Solenomya, finds that this primitive bivalve burrows with the 

 posterior end downward, thereby forming an exception to all 

 other known lamellibranchs. Solenomya swims actively through 

 the water by the combined action of the foot and valves of 

 the shell. 



Like several previous investigators, Mrazek (37) finds that 

 Branchipus is positively phototactic and ordinarily swims on 

 its back. This orientation was preserved after the removal 

 of the eyes. 



