372 0. C. Glaser and C. M. Sparrow 



found the percentages much higher. The results obtained from 

 the macerated material, in which discharge was complete, and 

 also instantaneous, show that media, such as glycerine, and sugar 

 solutions, either clog the pores, and make diffusion a slow process, 

 or else rnake the eversion of the thread so difficult that a higher 

 pressure than the normal one is needed to bring about explosion. 

 Both of these causes might be operative together, and, in addi- 

 tion, it must be remembered that the digestive processes in them- 

 selves might have the effects suggested, and might also alter 

 the constitution of the intracapsular contents. 



Hypertonic Solutions 



If the results already described support the osmotic theory, the 

 effect of hypertonic solutions completely demonstrates its correct- 

 ness. Not only do nematocysts fail to explode in such solutions 

 (Table II) but if left in them for a number of days, they can be 

 made to discharge in media too concentrated to bring about the 

 explosion of normal nematocysts. These results, which will, be 

 referred to again in another connection, can be explained only on 

 the assumption that by slow transfusion the intracapsular con- 

 tents are so changed by the hypertonic solutions, that the nemato- 

 cysts become able to absorb water from media more concentrated 

 than those toward which they are normally osmotically neutral. 



Negative External Pressure 



If the explosion of nematocysts is due to pressure from within 

 outward, as the osmotic theory requires, and as the effects of dis- 

 torting pressure seem to indicate is true, it follows that a negative 

 external pressure might result in explosion, particularly if, as is 

 conceivable, the capsules are in a state of tension. Negative 

 pressure of one atmosphere, produced by suction, gave entirely 

 negative results. This failure, however, is not traceable to a mis- 

 take in principle, but to the insufficiency of the negative pressure. 

 The osmotic pressure of sea-water is in the neighborhood of 22 

 atmospheres (Garrey '04), and as will be shown later, the pres- 



