26 G. H. Parker 



open, though occasionally they seemed to. Like the oscula, the 

 ostia were indifferent to seawater containing juice from the body 

 ' of Stylo tella itself. 



d. Heat and Cold 



Prepared fingers of Stylotella in which the ostial currents were 

 running vigorously continued to exhibit these currents after the 

 temperature of the seawater had been changed from 28° C. to 

 36° C, and fingers in which the ostia were closed at 28° C. opened 

 them after the sponge had been a few minutes in water at 35° C. 

 At 40° C. all currents, sub-dermal and oscular as well as ostial, 

 became rapidly feeble and then stopped, and at 45° C. these cur- 

 rents ceased abruptly as though the heat had caused the choano- 

 cytes to stop beating. This view is supported by the fact that 

 few fingers of Stylotella ever recovered after having been sub 

 jected to seawater at 45° C. for any length of time. Cold water 

 at 9.5° C. caused all currents to run more slowly, but did not 

 bring about a closure of the ostia. In fingers in which the ostia 

 were closed these organs did not open after having been a quarter 

 of an hour in seawater at 9° C. In these specimens the sub- 

 dermal and oscular currents became sluo;gish on reducing; the 

 temperature of the water, hence the effect of the low tempera- 

 ture was probably chiefly on the choanocytes. 



e. Light 



As in the case of the osculum, I have observed no effect from 

 intense sunlight or shadow on the opening or closing of the ostia. 



C. Movememts of the Body as a Whole 



Aristotle in the fourteenth chapter of his fifth book on the his- 

 tory of animals makes the interesting statement that the sponge 

 is supposed to possess sensation because it contracts if it per- 

 ceives any movement to tear it up and it does the same when the 

 winds and waves are so violent that they might loosen it from its 

 attachment. He further adds in his characteristic way that the 

 natives of Torona dispute this. The idea that the common 



