1903,] Action of the Poison of the Hydrophidce. 483 



impossible to get any further poison from it, even if it bite vigorously. 

 Yet if made to bite a small fish immediately after ejecting his poison, 

 the bite is fatal in a short time, showing how fatal a trace of it is. 

 The largest amount of poison obtained at a single bite was O023 

 gramme. The other species mostly gave a smaller quantity than the 

 Enhydrina. 



Effect of Heat on the Poison. 



On boiling a dilute solution of the poison, it becomes slightly 

 opalescent. After being boiled for 15 seconds, two minimal lethal 

 doses were recovered from, after slight symptoms had appeared, but 

 four minimal lethal doses proved fatal in a somewhat longer time than 

 with unheated poisons. After boiling for one minute, four minimal 

 lethal doses were recovered from after only slight symptoms. Thus 

 the poison is readily destroyed by boiling for a short time, but merely 

 bringing it to the boiling point does not materially affect its strength. 

 Some similar experiments with Cobra poison show that the latter is 

 slightly more resistent to heat than is that of the Enhydrina. 



Symptoms Produced by the Poison. 



The following symptoms are common to all the species yet tested, 

 no differences having been met with, except with regard to the exact 

 amount of the minimal lethal doses in different animals, which will be 

 dealt with presently. Briefly, the symptoms produced by the poison 

 of the Hydrophidse may be said to be identical with those caused by 

 cobra venom, with one very important exception, namely, that the 

 former venom has no appreciable action on the blood, which is a 

 marked feature of cobra toxin. In the case of warm-blooded animals, 

 such as rabbits, rats or birds, the symptoms produced by sea-snake 

 poisons are as follows. When minimal lethal, or slightly supra- 

 minimal lethal doses are given subcutaneously, there is always a long 

 period before any symptoms of poisoning occur, the time varying in 

 accordance with the dose from half an hour to several hours, in which 

 respect it resembles Cobra, and differs markedly from Daboia venom. 

 If large doses are given, the symptoms set in much earlier, and in 

 that case death rapidly results. The symptoms are best studied by 

 the use of small doses, when the first thing noticed is that the animal 

 remains quietly in one position, and soon begins to show signs of 

 drowsiness, closing its eyes at intervals. Next it begins to nod its 

 head, but every now and then appears to wake up again and opens its 

 eyes. In the case of birds — in which the symptoms can be best seen — 

 the subject of the experiment next sits clown on the floor of the cage, 

 and although it can be made to stand up if disturbed, yet there is now 

 evident commencing muscular weakness, and it can only walk with an 



