70 BACTERIA. 



causation and prevention of wine disease now turned his 

 attention to the ravages of the " spot " disease or " pebrine" 

 amongst silkworms, a disease that at one time threatened 

 to destroy the flourishing silk industries of France. The 

 organisms found in this disease had already been described 

 by Naegeli as Nosema Bombycts, and by Latour as Panhis- 

 tophyton, small, glistening, oval corpuscles which appeared to 

 be endowed with life and to lead a parasitic existence in the 

 tissue of the silkworm caterpillars. Pasteur was able to 

 demonstrate their presence not only in the butterflies which 

 develop from these worms, but also in the eggs they laid, 

 and he found that where any one of the three forms was 

 affected, the corpuscles were passed on to the next stage. 

 He was able to show that they increased in the body, that 

 they were the cause of the disease, and that by careful ex- 

 amination and destruction of the affected eggs and the 

 preservation of the healthy ones, the disease could gradually 

 be eliminated. He found that another disease, the lethargy 

 of silkworms, was also probably caused by the presence of 

 micrococci, arranged in the form of chains, in the intestinal 

 canal of the worms. Pasteur had thus succeeded in showing 

 the relationship between certain micro-organisms and certain 

 wine diseases, but he had also been able to demonstrate a 

 causal relation between certain lowly-organized, parasitic 

 organisms and a special disease in animals or insects. He 

 had, in fact, demonstrated that certain specific organisms, 

 endowed with definite morphological and physiological 

 characters, gave rise by their presence to specific and 

 characteristic diseases ; he had by observation and experi- 

 ment extricated the theory of a living contagium from a 

 condition of chaos, and he had assigned to definite organ- 

 isms, each a special role in the production of certain forms 

 of fermentation, of putrefaction, and of disease ; and although 

 much was still left, and still remains to be done, in the 

 identification and classification of those organisms, he had 

 separated a few distinct forms, and instead of assigning to 

 these a general and common action in the production of the 

 above processes, he had allotted to each one its own part. 

 This he was able to do with such clearness and to place his 

 experiments so lucidly before the scientific world, that there 

 could be no doubt as to his meaning ; the consequence 

 being that he soon secured a large following of enthusiastic 



