Reactions of Sponges IQ 



boiled vigorously for some time to discharge the contained gas and 

 after this had been accomplished the water was set aside in a 

 tightly stoppered vessel to cool. Sponges in a current of normal 

 seawater and with open oscula were suddenly subjected to a cur- 

 rent of seawater thus deoxygenated drawn with as little exposure 

 to the atmosphere as possible from the storage vessel. Their 

 oscula closed in from ten to twelve minutes. On returning them 

 to a current of ordinary seawater, they reopened their oscula in 

 from fifteen to twentv-five minutes. Lack of oxygen will there- 

 fore cause the oscula to close. 



d. Heat and Cold 



The seawater in which Stvlotella was found living in the neigh- 

 borhood of the laboratory in June and July had a temperature of 

 about 25° to 28° C. In a current of this water the oscula of Stvlo- 

 tella will often remain open many hours together. If the tem- 

 perature of the current was changed to about 35° C, the oscula 

 often constricted slightly, and the same was true at 40° C. At 

 45° C. the oscula in five or six minutes went into a state of flabby 

 contraction, and if this temperature was maintained for a con- 

 siderable time much of the sponge died. At temperatures lower 

 than the normal, from 25° to 9° C, the oscula remained open and 

 outward currents could be demonstrated. Thus low tempera- 

 tures were apparently without effect on the oscula and high tem- 

 peratures called forth a partial contraction. 



e. Light 



Sudden changes from the most intense sunlight to the most com- 

 plete darkness were not followed by any observable movement of 

 the oscula in Stylotella, which in this respect follows the general 

 statementmadeby Minchin ('00, p. 89), that adult sponges are not 

 sensitive to light. 



B. Movements of the Dermal Pores orOstia 



7 he movements of the dermal pores or ostia in Stvlotella were 

 not so easilv demonstrated as those of the oscula were. The small 



