166 ANNUAL OF SCIENTIFIC DISCOVERY. 



investigators whose lives have been perilled by the self-administration of 

 dangerous reagents. As a rule, these investigations are made, in the first 



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instance, on the lower animals ; but the results so obtained only give a 

 very slight approximation to what would be the nature of the action of 

 these bodies on the human frame. 



We know absolutely nothing of the different constitutional powers in 

 the different animals, so that our only means of acquiring a knowledge 

 of the therapeutical action of remedies is by direct experiment in every 

 case. For example, the goat and the sheep are so slightly different in 

 structure and organization that it is difficult even to discover a well-de- 

 fined specific distinction between the two animals. Nevertheless, many 

 substances are fatal to the sheep that the goat eats with impunity. A 



Smt will eat at a meal a sufficient quantity of laurel twigs (Cerasus 

 auro cerasus) to destroy the life of a cow, a ruminating animal, whose 

 organization closely resembles its own. In the same manner, tobacco 

 one of the most fatal of all poisons to the human frame is eaten by 

 goats and monkeys with great avidity, and without any apparent evil 

 consequences. Sir Emerson Tennant, in his work on Ceylon, referring 

 to the invulnerability of the mongoose to the bites of poisonous serpents, 

 says, " Such exceptional provisions are not without precedent in the 

 animal economy ; the hornbill feeds with impunity on the deadly fruit 

 of the strychnos; the milky juice of some species of euphorbia, which is 

 harmless to oxen, is invariably fatal to the zebra ; and the tsetse fly, the 

 pest of South Africa, whose bite is mortal to the ox, the dog, and 

 the horse, is harmless to man and the untamed creatures of the forest." 



Among the most important new remedies which science has bestowed 

 upon medicine may be mentioned the preparations of the element bro- 

 mine. This, as is well known, belongs to the same group of elements 

 as chlorine, iodine, and fluorine ; each of these, though perfectly capa- 

 ble of replacing each other in chemical combinations, has a totally dif- . 

 ferent action on the vital organism. 



Chlorine is an essential to the life of all animals, and is supplied in 

 the form of common salt, chloride of sodium. Iodine is, both when sim- 

 ple and in combination, a powerful stimulant, exciting the glandular 

 system. 



Fluorine, though never yet isolated, is in some of its combinations a 

 powerful poison. 



Bromine has been discovered by Dr. Gibb to possess, when admin- 

 istered in the form of bromide of ammonium, Br N H 4 , a power of pro- 

 ducing insensibility or even partial paralysis of the nerves going to the 

 glottis and larynx, or organs situated at the top of the windpipe. This 

 knowledge has been at once applied to practical medicine. The pain- 

 ful disease known as whooping-cough owes its chief danger and discom- 

 fort to spasm of the nerves going to the respiratory organs. It has been 

 found that the administration of a few grains of bromide of ammonium 

 three times a day has the effect of allaying this spasm, and so prevent- 

 ing the most dreaded symptoms of the disease. 



Having alluded to the newly-discovered metal, thallium, it may be 

 as well to mention that M. Lamy states that continued investigation 

 into its properties has resulted in extreme lassitude and pain in the 

 lower limbs. With a view of determining its real influence on the ani- 

 mal economy, he has administered it to the lower animals, and he men- 



