1 6 G. H. Parker 



observation is in accord with what Merejkowsky ('78, p. 13) 

 found to be true of Rinalda; if the oscular edge of the sponge is 

 struck several times with a needle, the osculum quickl) contracts 

 and remains so several minutes, after which it more slowly opens. 

 The same is said by Merejkowsky (p. 14) to occur in Suberites. 



As might be inferred from the statements already made, the 

 injuries done to one finger of Stylotella have no influence on the 

 condition of the oscula of neighboring fingers, nor do injuries 

 inflicted on the com.mon flesh of the colony between fingers influ- 

 ence the oscula of these fingers. 



The nature of the stimulus produced by cutting the flesh of a 

 sponge seems to be rather mechanical than otherwise. Such an 

 injury besides mechanically disrupting tissues does little more 

 than liberate juices from the substance of the sponge. These 

 juices, however, when collected and discharged artificially and 

 with great freedom in a normal sponge with open oscula, do not 

 cause the oscula to close. I am therefore led to believe that the 

 closing of the osculum on injury to an adjacent part of the sponge 

 is due to the mechanical disrupting of tissues rather than to the 

 eff'ects of the juices that are liberated. If, however, the stimulus 

 from the injury is chiefly mechanical, it results in a very difi^erent 

 form of response from that due to currents, for the latter cause an 

 opening of the osculum while the former induce its closure. 



c. Chemical Stimulation 



Since the oscular sphincter of Stvlotella is made up of tissue 

 that has a striking resemblance to smooth muscle, 1 tried the 

 eff^ects of a number of drugs on this sphincter to ascertain whether 

 or not they influenced this organ as they did the smooth muscle of 

 the higher animals. The drugs used were ether, chloroform, 

 strychnine, cocaine, and atropin dissolved in seawater. This 

 water was then used in the circulating; apparatus already described 

 (p. 12), so that sponges could be exposed to it in currents. I also 

 tested in the same apparatus the effects of diluted seawater, of 

 freshwater, and of seawater deprived of its oxygen by boiling. 



When a sponge whose oscula were open in a current of pure sea- 

 water suddenly had this changed for a current of seawater con- 



