106 NATURAL \SCTENCE, FEB., 
to the medical faculty ; and, like Pasteur’s, Dr. Maclagen’s explanation 
does not account for the fact that the microbe can be grown outside 
the body where the nidus does not exist. 
And how is the change in the organism supposed to be brought 
about? Pasteur believes the attenuation of the virus to be due to the 
action of the oxygen of the air, except, of course, in those cases where 
it is passed though a series of animals, or where the change is partly 
attributed to heat; but it is difficult to understand in what way 
oxygen could alter the character of a living organism so as to cause 
it to produce varying effects. Is there any case known of an organism 
altered in such a way? There are three cases among the organisms 
we are considering, in which the essential characters of the species are 
said to have been thus changed by the method of cultivation :— 
(1.) Buchner has stated that by successive cultivations he has 
transformed the bacillus of anthrax into the harmless hay bacillus. 
He likewise claims to have transformed the hay bacillus into the 
deadly bacillus of anthrax. 
(2.) A bacillus found on the seeds of Alexus precatorius (an Indian 
and South American leguminous plant used in certain diseases of the 
eye), and apparently identical with the hay bacillus, is, according to 
Sattler, capable of being transformed into a disease-producing form. 
An infusion of the seeds, known as jequirity, is made and several 
cultivations of the bacillus started from this in the ordinary sterilised 
media. The change in the nature of the bacillus is supposed to be 
effected by growth in the original jequirity fluid, and to be retained 
in the successive cultivations, since all these were found to produce 
severe ophthalmia; and not only did Sattler suppose the original 
jequirity bacillus was thus modified so as to produce disease, but 
that germs of other harmless forms which might settle down in the 
jequirity solution likewise became pathogenic. 
(3.) The third case is that of a common mould, Aspergillus, which 
has been found to produce death in rabbits when its spores are 
introduced into their systems, although not in the proper sense of the 
term a pathogenic form. 
Dr. Klein has carefully examined these cases, and repeated the 
experiments, with the result that all break down as examples of the 
change of septic into pathogenic microbes. ‘I feel sure,” he says, 
‘‘any one might as soon attempt to transform the bulb of the common 
onion into the bulb of the poisonous colchicum.” Other observers 
have corroborated Klein’s conclusions. 
Ought we, then, to believe that by a series of cultivations a 
microbe can lose the power of producing disease which it once 
possessed ? 
If the microbes of disease can be altered so as to produce a 
modified disease, it ought to be possible to produce, say, a lactic acid 
microbe, which would produce a modified lactic fermentation ; and 
further, such a modified fermentation should protect the liquid from. 
