SEPTE3IBER 25, 1896.] 



SCIENCE. 



425 



was strongly urged to publish before he was 

 himself disposed to do so, and we cannot 

 but regret that he yielded to the pressure 

 put upon him. 



But though Koch's sanguine anticipations 

 were not realized, it would be a great mis- 

 take to suppose that his labors with tuber- 

 culin have been fruitless. Cattle are liable 

 to tubercle, and, when affected with it, may 

 become a very serious source of infection 

 for human beings, more especially when the 

 disease affects the udders of cows, and so 

 contaminates the milk. By virtue of the 

 close af&nity that prevails between the lower 

 animals and ourselves, in disease as well as 

 in health, tuberculin produces fever in tu- 

 bercular cows in doses which do not affect 

 healthy beasts. Thus, by the subcutaneous 

 use of a little of the fluid, tubercle latent in 

 internal organs of an apparently healthy 

 cow can be with certainty revealed, and the 

 slaughter of the animal after this discovery 

 protects man from, infection. 



It has been ascertained that glanders pre- 

 sents a precise analogy with tubercle as re- 

 gards the effects of its toxic products. If 

 the microbe which has been found to be the 

 cause of this disease is cultivated in appro- 

 priate media it produces a poison which has 

 received the name ofmallein, and the sub- 

 cutaneous injection of a suitable dose of 

 this fluid into a glandered horse causes 

 striking febril symptoms which do not oc- 

 cur in a healthy animal. Glanders, like tu- 

 bercle, may exist in insidious latent forms 

 which there was formerly no means of de- 

 tecting, but which are at once disclosed by 

 this means. If a glandered horse has been 

 accidentally introduced into a large stable 

 this method of diagnosis surely tells if it has 

 infected others. All receive a little mallein. 

 Those which become affected with fever are 

 slaughtered, and thus not only is the dis- 

 ease prevented from spreading to other 

 horses, but the grooms are protected from a 

 mortal disorder. 



This valuable resource sprang from 

 Koch's work on tuberculin, which has also 

 indirectly done good in other ways. His 

 distinguished pupil, Behring, has expressly 

 attributed to those researches the inspira- 

 tion of the work which led him and his fa- 

 mous collaborateur, the Japanese Kitasato, 

 to their surprising discovery of anti-toxic 

 serum. They found that if an animal of a 

 species liable to diphtheria or tetanus re- 

 ceived a quantity of the respective toxin, so 

 small as to be harmless, and afterwards, at 

 suitable intervals, successively stronger and 

 stronger doses, the creature, in course of 

 time, acquired such a tolerance for the poi- 

 son as to be able to receive with impunity 

 a quantity very much greater than would 

 at the outset have proved fatal. So far we 

 have nothing more than seems to corre- 

 spond with the effects of the increasingly 

 potent cords in Pasteur's treatment of 

 rabies. But what was entirely new in 

 their results was that, if blood was 

 drawn from an animal which had ac- 

 quired this high degree of artificial im- 

 munity, and some of the clear fluid or 

 serum which exuded from it after it 

 had clotted was introduced under the 

 skin of another animal, this second animal 

 acquired a strong, though more transient, 

 immunity against the particular toxin con- 

 cerned. The serum in some way counter- 

 acted the toxin or was antitoxic. But, 

 more than that, if some of the antitoxic 

 serum was applied to an animal after it had 

 already received a poisonous dose of the 

 toxin it preserved the life of the creature, 

 provided that too long a time had not 

 elapsed after the poison was introduced. 

 In other words, the antitoxin proved to be 

 not only preventive but curative. 



Similar results were afterwards obtained 

 by Ehrlich, of Berlin, with some poisons 

 not of bacterial origin, but derived from 

 the vegetable kingdom ; and quite recently 

 the independent labors of Calmette, of 



