176 



KNOWLEDGE 



[August 1, 1896. 



February he commenced injecting a clean horse with 

 one-fifth of the minimum lethal dose. The next injection 

 of one half the minimum lethal dose was given seven days 

 later ; then three-fourths of that quantity five days after 

 this. He went on gradually increasing the dose in this way 

 for four mouths and a half. Thetirst injection caused general 

 disturbance and rise of temperature, but the subsequent 

 ones had no bad efl'ect, except the local symptoms of 

 cutaneous oedema and necrosis of small patches of skin at 

 the point of injection. He obtained the blood serum from 

 this immunized horse, after the long interval of experiments, 

 by drawing oil" some from its jugular vein. He found that 

 a hundredth and even a thousandth part of a cubic 

 centimetre per kilogramme of animal was sufficient to 

 prevent death from the minimum lethal dose of the 

 venom. The antivenine obtained from the horse was 

 found to be twice as powerful as that from the rabbit. 

 The dose last given to the horse may have been fifteen 

 times the minimum lethal dose, so that antivenine can 

 evidently be obtained from the horse by administering 

 that quantity of the poison. Although experiments may 

 yet prove that more powerful antivenine might be desired, 

 yet that obtained from the liorse is quite powerful 

 enough for counteracting the poison of snake-bites in 

 man. 



Already a quantity of this antivenine is on its way to 

 India for use there. Prof. Fraser has put it up in two 

 forms, a liquid and a dry form. The dry state has an 

 advantage over the other in more ways than one — it goes 

 into less bulk, is practically indecomposable, and loses 

 none of its antitoxic properties by being dried. On the 

 other hand, some which was put up in the liquid form 

 underwent decomposition, or at least, became quite turbid 

 in appearance, though at first quite clear. Now if that 

 happens in our temperate climate, it would be much more 

 likely to decompose in tropical countries. Accordingly 

 the dry antivenine will ultimately be the exported product 

 for use in India. 



Prof. Fraser has observed a peculiar fact, viz., that 

 dietary has an effect upon venom poisoning : for example, 

 if an herbivorous animal be put upon flesh diet, the effect 

 of venom upon it is much lessened. To prove this, he 

 took a family of young white rats, and for seven weeks fed 

 them entirely upon flesh food, except occasionally when a 

 little vegetable food was given to keep them in good health. 

 One of these rats had an injection of one and a half times 

 the minimum lethal dose to commence with, and there 

 was very little or no change produced by the poison. 

 Another had twice the minimum lethal dose injected ; it 

 recovered after a short illness. The other rats died from 

 ill-health occasioned by the change of dietary. 



By another set of experiments. Prof. Fraser hag found 

 that the deadly efl'ects of serpent's venom is supposed to be 

 due to its efl^ect on the blood. Venom is almost inert when 

 introduced into the stomach or any other part of the 

 alimentary canal. A cat was made to swallow one-fifth 

 of the minimum lethal dose, then one-third, and then one- 

 half, and so on, until on the one hundred and sixteenth day it 

 received into the stomach at one time a dose eighty times 

 larger than what would have killed a clean cat by injection 

 — yet no observable disturbance was produced by these 

 doses. To Lave carried theje experiments any further 

 would have required upwards of a gramme of venom. This 

 he could not afford with a rapidly diminishing supply. 

 This cat, so far immunized by the stomach, was then given 

 under the skin an injection of one and a half times the 

 minimum lethal dose ; and no bad effects were produced 

 except the merely local ones. In the curious case of a cat 

 which vras being immunized while jiregnant, it was found 



that the kittens, after birth, also became immunized 

 through the mother's milk. One of the kittens received a 

 dose considerably above the minimum lethal dose and 

 recovered. 



Important evidence in favour of the administration of the 

 venom into the animal's stomach, for the sake of having it 

 immunized, has been obtained with white rats. One received 

 by the stomach a thousand times the amount which would 

 have been a minimum lethal dose when injected under the 

 skin into the blood. Afterwards, the same rat had twice 

 the minimum lethal dose injected subcutaneously, and it 

 became sleepy for a time, but soon recovered its hilarity. 

 Accordingly, when snake's venom is introduced into the 

 stomach it does not produce any active poisoning effects; 

 but some of it seems to become absorbed into the animal's 

 blood so as to assist in the immunization. This may 

 account for the immunity from snake-bites said to be 

 enjoyed by some of the snake-charmers of India, who eat 

 the dried poison glands of the snakes. 



Snakes themselves seem to have some substance in their 

 blood which renders them impervious to the effects of the 

 poison. This may probably be got from venom shed from 

 the poison-glands, and absorbed through the mucous 

 surfaces of the mouth ; or it may be absorbed by the blood- 

 vessels and lymphatics passing to and from the glands. In 

 some cases it may be secured by serpents devouring other 

 members of their tribe, thereby absorbing venom by the 

 stomach. 



Prof. Fraser has obtained a living venomous snake, 

 and he intends to test its blood for antivenine ; but as 

 it has been shedding its skin since he received it, he has 

 put ofi' the experiments till the animal recovers its good 

 health. 



It is now within the region of certainty that at no distant 

 date this indefatigable snake-charmer of a scientific 

 character will be able to send out to India sufficient 

 quantities of dried antivenine from the immunized horse 

 to be of inestimable service to those who are exposed to the 

 bites of venomous snakes in that extensive country. The 

 experiments, interesting and curious as they undoubtedly 

 are to the ordinary reader, are of paramount importance 

 to humanity ; and Prof. Fraser's discovery is sufficient to 

 give him a distinguished place among the advancers of 

 medical research. Should he yet be able to discover the 

 chemical constituents of the antivenine so as to manu- 

 facture it by chemicals, his success will be complete. All 

 interested in the saving of life must wish him every success 

 in his laudable undertaking. 



LEAPING BEETLES. 



By E. A. BuTLEK, B.A., B.Sc. 



THE power of springing up into the air, and thus 

 taking long leaps from place to place, is not a very 

 prevalent accomplishment in the insect world, and 

 amongst British insects it is possessed by not more 

 than about four per cent, of all the species. 

 Besides occasional instances here and there, such as the 

 fleas and the cheese-jumper, in the order Diptera, there 

 are certain groups of greater or less extent that are dis- 

 tinctly characterized by the habit. The best known of 

 these are no doubt the grasshoppers amongst the 

 Orthoptera, the frog-hoppers amongst the Homoptera, and 

 the spring-tails, which constitute the order CoUembola, 

 minute, soft-bodied creatures, found in great abundance in 

 grassy places, and under stones, logs of wood, dead leaves, 

 moss, etc. The gymnastic mechanism in both the spring- 



