274 ^- ^- Glaser and C. M. Sparroiu 



pable of changing the concentration of the solution through which 

 it passes, on account of the compensatory effect of the rapid revers- 

 als in direction. 



RATE OF EXPLOSION 



The fact that the rate at which explosion takes place may be 

 greatly modified by treating the capsules with glycerine and sugar, 

 suggested the possibility of controlling the eversion of the thread 

 in other ways. If the osmotic conception is correct, a moderate 

 increase in the concentration of a solution should reduce the speed 

 of the discharge, and a great increase should prevent explosion 

 altogether. Both of these effects were obtained, though under 

 influence of heat, the capsules continued to discharge in media 

 too concentrated to allow explosion at ordinary temperature. 



The reduction in the speed obtained by the use of concentrated 

 sea-water, and other media of high osmotic pressure, made pos- 

 sible certain observations on the eversion of the thread which are 

 in complete harmony with the osmotic theory. In such media, 

 when the dilution is just sufficient to bring about explosion, one 

 can see that during the process of eversion, the thread is cast out 

 suddenly, but only to about two-thirds its length. A brief period 

 — less than a second often — of inactivity, due no doubt to the im- 

 mediate relief of pressure, ensues, and then the remainder of the 

 thread is everted. To observe this effect one must use a medium 

 only a trifle less concentrated than that from which the nemato- 

 cysts were taken. 



VARIATIONS IN THE EXPLOSIVE PRESSURE 



In practically all of the experiments on isolated nematocysts, 

 it was noticed that not all of the threads are everted under cir- 

 cumstances under which most of the capsules explode. At cer- 

 tain concentrations no explosions occur; if the solution is diluted, 

 a few incomplete or slow discharges occur; fuither dilution in- 

 creases both the number and the rate of the discharges, and finally 

 a point is reached at which the great majority explode. Even 

 here, however, a few remain unaffected unless the medium is 



