I58 GEORGE T. MCNAIR. 



did not reopen until they were placed in running water. He 

 was able to prove that the mechanical stimulus of the currents 

 of water on the outlet tip of the finger where the osculum was 

 located, caused it to open. The oscular closure seems to be a 

 protective adaptation of Stylotella, which is a shallow salt-water 

 species frequently left exposed to the air when the tide is out. 

 Since the fresh-water sponge is never exposed to such tidal 

 conditions, one would not expect to get the same reactions. 



Brushing. 

 Rubbing the sides of the chimney with a needle, prodding it 

 gently, or even inserting the needle into the mouth of the osculum 

 and rubbing the inside of the chimney, caused no noticeable 

 reaction; however, if the needle were carefully rubbed around 

 the edge of the mouth of the osculum, an immediate contraction 

 of the orifice would follow and it would continue to contract for 

 about three minutes. Following the contraction of the sphincter 

 at the orifice a wave of contraction would travel down the 

 chimney although the amount of contraction would be less than 

 at the orifice. On a chimney of 1.5 mm. length it would require 

 about six seconds for this wave to run from the tip to the base 

 of the osculum. In the next three or four minutes it would 

 again expand to its original size. The edge of the mouth of the 

 osculum, therefore, seems to be more sensitive than the rest of 

 the chimney. Concerning the reactions of Stylotella, Parker 

 states that stroking an open osculum with a bristle or brush does 

 not cause it to close, but if it is closed, this treatment may at 

 rare intervals induce it to open. 



Sharp Blow. 

 Several times while getting the electrodes into position to work 

 with the inductorium one of the wires of the electrode would 

 catch on a spicule and, springing loose, strike an oscular chimney. 

 Each time the entire chimney would shrivel up immediately in 

 a more or less collapsed condition, but within twenty or thirty 

 minutes it would be open and functioning as before. 



Cutting. 

 Cutting into the body seemed to have no effect in the way of 

 induced movements. With a small scalpel an incision was made 



