1 8 G. H. Parker 



could not be distinguished in its action on the osculum from pure 

 seawa ter. 



A solution of one part of atropin to one thousand parts of sea- 

 water checked the rapichtv of oscular contraction much as the 

 stronger of the two effective solutions of cocaine did, and a solu- 

 tion of one part of atropin in ten thousand parts of seawater could 

 not be distinguished from pure seawater. 



Although the observations on the actions of these various drugs 

 as given in the preceding paragraphs are insufficient to admit of 

 any detailed analysis, the results are in agreement with what is 

 known of the action of these materials on smooth muscle. To 

 this type of muscular tissue chloroform is more destructive than 

 ether, strychnine renders it especially contractile, and cocaine and 

 atropin inhibit this property somewhat (Grotzner, '04, p. 65). 

 This evidence, therefore, supports the view that the sphincter 

 myocytes of sponges are in the nature of primitive smooth muscle 

 fibers. 



The effects of dilute seawater and of freshwater itself on the 

 oscular mechanism were tried in the circulating apparatus. If a 

 sponge whose oscula have been open in a current of seawater for 

 over an hour is flooded with a current of water composed of one- 

 fourth fresh water and three-fourths sea-water, the majority of the 

 oscula contract somewhat in twenty minutes, after which they 

 remain partly open. In a mixture of half freshwater and half sea- 

 water the oscula contract but do not close completely. In three- 

 fourths freshwater and one-fourth seawater, the oscula contract in 

 about seven minutes but do not close. In pure freshwater, they 

 remain expanded as though dead, but even after having been 

 twenty-four minutes in freshwater, such sponges will revive in 

 running seawater, though their oscular collars are seriously 

 damaged and are regenera ted only after several days. As St ylotella 

 inhabits the shallow waters near the shore, it must often be sub- 

 jected after heavv rains to the effects of diluted seawater, but, as 

 the observations recorded above indicate, it would not be seriously 

 damaged by these changes and would probably protect itself 

 against them by oscular constriction. 



To prepare seawater free from oxygen a large volume was 



