Specific Gravity and Luminescence in Noctiluca, etc. 251 



similar experiment was tried with animals subjected to m/8 ether for 

 10 minutes with the same result. In these experiments the cell-mem- 

 branes were destroyed, allowing oxygen to enter the cell directly, and 

 the effect was different for the anesthetized cells and the control. The 

 anesthetic must therefore act, not on the cell-membrane by preventing 

 oxygen from entering the cell, but directly upon the cell interior, prob- 

 ably attacking the mechanism of the utilization of oxygen in the cell. 

 A criticism of the foregoing experiments might be offered — that, 

 owing to the length of time that the cells were subjected to the anes- 

 thetic, substances present in the cells might be used up and the cells 

 be fatigued. The following experiment showed that such was not the 

 case: Three lots of animals were put into tubes with sand, two im- 

 mersed in m/8 ether and the third in sea-water. One of the ether 

 tubes was very slightly agitated almost immediately and did not 

 increase in brightness as normal animals do on slight agitation, showing 

 that the animals were narcotized. The other ether tube was shaken 

 vigorously at once so as to break up the animals, and it became slightly 

 brighter. The control tube with sea-water, when also shaken vigor- 

 ously at the same time, became markedly brighter, showing a striking 

 contrast to the other two tubes. In this experiment there was not 

 sufficient time for any substances in the cells to be used up, and yet 

 the narcotized cells gave a much weaker light than the control lot on 

 admission of oxygen by destroying the membranes. The evidence from 

 these experiments on Noctiluca would therefore argue against the mem- 

 brane theory of anesthesia, since the anesthesia of light-production 

 takes place independently of the cell-membrane; the effect of the 

 anesthetic seems to be upon the mechanism of the oxidation process 

 inside the cell. 



SUMMARY. 



1. The specific gravity of Noctiluca is less than that of sea-water, 

 so that normally the animals float at the surface. Since they contain 

 no air-bubbles or large oil-drops, their lower specific gravity must be 

 due to a lower salt-content than that of sea-water. When placed in a 

 mixture of 4 sea-water to 6 fresh-water, the animals sink, their salt- 

 content being now greater than that of the surrounding medium, but 

 later they rise to the surface, a process independent of the movement 

 of the tentacle. They therefore absorb water until their salt-content 

 is again less than the medimn, thus reestablishing their normal relation 

 to the surrounding medium. This water must be absorbed against 

 the osmotic pressure of the salts of sea-water, a process contrary to 

 physical laws. The animals can not only lessen their specific gravity, 

 but can also increase it, as shown b}^ the fact that they sink to the 

 bottom of the sea on windy days. Anesthetics, acids and alkalies, 

 KCN, and the pure salts of sea- water do not interfere with this regu- 



