498 SUMMARY OF CURRENT RESEARCHES RELATING TO 



it was observed showed no other peculiarities, and were of about the 

 same calibre as the rod bacteria usually observed. 



The fact is noted as affording proof that bacteria can take up 

 minute solid jiarticles through their walls. 



Bacterium decalvans.* — Dr. Thin also describes this organism, 

 which is associated with the destruction of the hair in Alopecia 

 areata. Having found bacteria adherent to the roots of extracted 

 hairs, he subjected hairs in six selected cases to processes designed to 

 demonstrate the existence of organisms should they be present in the 

 substance of the diseased hairs. In five out of the six cases, an object 

 was observed in the hairs which he believed was a Bacterium ; their 

 size and form were the same, and they had the refractive qualities of 

 bacteria. 



In seven consecutive cases disease was at once and definitely arrested 

 by a treatment designed to destroy the vitality of any bacteria which 

 might be present on the surface of the skiu, and at the same time to 

 present a mechanical obstacle to their progress in growth from one 

 hair-follicle to another. 



Mitigation and Renewed Activity of Organized Poisons-t — 



The application of atmospheric oxygen to the mitigation of the activity 

 of bacterium poisons, already shown to promote this object, is now 

 lurther dealt with by L. Pasteur, and Messrs. Chamberland and Eoux. 

 The mycelium of anthrax — unlike that of fowl-cholera and the 

 yeast bacterium — becomes resolved, after from twenty-four to forty - 

 eight hours' growth, into spores; these germs undergo no loss of 

 vitality or virulence by exposure to the air, while the mycelium is 

 affected by this process ; hence to diminish the virulence of the 

 poison it should be attacked under circumstances which prevent 

 its passing into the spore condition ; a temperature not exceeding 

 16° C, or one between 42° C and 43° C. furnishes those circum- 

 stances, at any rate for considerable periods of time. At the latter 

 temperature the growth dies in a month, and after eight days it 

 has lost its deadly properties ; in the same way as the fowl-cholera 

 bacterium, it passes through stages of mitigation of its power until 

 the time when this power is entirely lost ; in the same way also the 

 mitigated poison constitutes a vaccine capable t f protecting from the 

 disease. On the other hand, it is possible to restore to this poison 

 its full activity ; this is effected by inoculating with it a guinea-pig 

 one day old, and transferring its infected blood to a similar animal, 

 and so on ; the animals at this age are invariably killed by the 

 mitigated poison, and after this process had been repeated several 

 times, the poison recovers its full vigour, and will kill even sheep. 

 Similarly the mild form of the fowl-cholera poison may be restored 

 to full activity by passing it through those small birds, as sparrows, 

 canaries, &c., to which it is immediately fatal. These considerations 

 furnish an explanation of the so-called spontaneous appearance of 

 certain epidemics ; thus the plague, which is confined to certain 



* Proc. Royal Boc., xxxi. (1881) pp. 502-3. 

 t Comptes Rendus, xcii. (1881) pp. 429-35. 



