The Physiology of Nematocysts 371 



and potassium and mercury salts, are all to be expected. Some 

 of the other results, however, require a word of comment. 



Alcohol, ether, even if effective, chloroform and chloretone, 

 used because employed in the previous experiments on living 

 tentacles and acontia, bear neither way on the osmotic theory. 

 The action of strong acids and of ammonia remain to be explained. 

 Acids are chemically very active, and it is conceivable that upon 

 penetration into the nematocyst they affect a decomposition of the 

 intracapsular contents, thus increasing the number of molecules 

 present, and hence the internal pressure. Since the H ion is the 

 active one, it is possible that the membrane is specifically per- 

 meable to it. 



The effect of acids, however, may be explained in the same way as 

 the action of ammonia. The latter is effective possibly oh account 

 of its power of disintegrating tissues. If the capsule is weakened 

 at the point where the thread is introverted — a point normally 

 weak — eversion is likely to occur, for as will be shown later, the 

 capsular contents themselves exert a high pressure. 



The effect of distilled water on nematocysts which have been 

 treated with a saturated solution of sugar, is due to the fact that 

 sugar probably "gums up" the pores of the capsules. Other 

 agents do the same thing, and it is for this reason that the Physalia 

 material was not used, although in the course of time it would 

 probably have given the same results. This is indicated by the 

 following observations. 



In suspensions made in distilled water, from dessicated Physalia 

 nematocysts, as well as from those preserved in glycerine, it was 

 noticed that the older the suspension, the greater the number of 

 completely discharged nematocysts. This increase was so great 

 that in the course of several days the exploded ones began to 

 outnumber those intact. This phenomenon pointed to slow 

 osmotic interchange between the capsular contents and the sur- 

 rounding medium. Grosvenor, in dealing with pieces of actinian 

 tentacle teased up in a half concentrated sugar solution, found, 

 when the sugar is washed out with distilled water, that "never 

 more than approximately 20 per cent" of the nematocysts dis- 

 charge themselves. Had he waited, he would no doubt have 



