KLEIN AND PASTEUR. on5 
Encouraged by this result, Pasteur next turned his attention to 
anthrax. There are two modes in which micro-organisms spread 
themselves. One is by a process of cell division, which may be 
likened to the growth of branches on trees and to the production 
of new trees from branches which have been separated from the 
parent and caused to take root in the earth. The other mode is by 
the production of rows of brilliant corpuscles or spores along the 
rod-like bacilli, like the sorz or spangles on the backs of fern fronds. 
Having given birth to these spores the parent rods break up, each 
of the spores being capable of producing a new crop. This method 
may be likened to the production of new plants from seed. The 
Bacillus anthracis not only grows by cell division but produces 
spores. As these spores, like ordinary seeds, retain their vitality 
and specific character under conditions which would kill or modify 
the parent plants, Pasteur came to the conclusion that it would be 
desirable to eliminate them from his artificial cultures. In his 
original paper he claims to have found that, grown at 42 deg. 
Centigrade, the Bacllus anthracis produces no spores, and that, 
having thus got rid of the spores, he has been able so to “attenuate” 
the sterile bacilli as to convert them into a “vaccine” against 
anthrax, just as he had already produced from the virus of chicken 
cholera a vaccine against that disease. According to M. Paul Bert, 
not less than 400,000 sheep have been in consequence successfully 
vaccinated in France against a disease which previously cost the 
farmers of France about 41,000,000 per annum. It is not denied 
that failures have occurred, and considering the nicety of the pro- 
cess and the still mysterious character of the whole subject, this 
is not surprising. It cannot as yet be said, either, how long the 
protective influence lasts. But meantime there is the undoubted 
fact that the ruinous mortality amongst sheep in France from 
anthrax has been enormously reduced. Pasteur asserts that the 
“attenuating ” influence by means of which he has succeeded in 
obtaining these results is traceable simply to the presence of oxygen ; 
and should this prove to be so, the suggestiveness of the discovery 
is very great. Assuming, for instance, it may be argued, the 
presence of organic matter in ill-ventilated sewers, may not the 
absence of a sufficient supply of oxygen result in the conversion of 
the harmless saprophytes of decay into the deadly parasites of 
typhoid and other diseases? Or, again, given existence in ill-ven- 
tilated dwellings and close bedrooms, or inefficient aeration of the 
lungs in consequence of dusty employment and sedentary habits, 
may not some harmless saprophyte be converted into the parasite 
which Koch has found to be associated with consumption ? 
After this explanation, which will, it may be hoped, enable the 
non-scientific reader to understand the problems presented for 
examination, and to realise their extremely interesting nature, the 
