306 THE EVOLUTION OF LIFE 

a contagious mode of origin. Ina recent address? 
by a distinguished pathologist, Professor Adami of 
Montreal, he cites a very distinct case in which 
certain common Bacteria under the influence of 
altered conditions of life have, within a compara- 
tively brief period, had their metabolic processes 
completely altered; so that, as he says, ‘“ From 
having been perfectly harmless they are now 
pathogenic, and can set up disease.” He then 
makes the following remarks: ‘‘What is to be 
said concerning the tubercle bacillus in this con- 
nection? In the first place we may have the 
complete assurance that Adam was not created 
suffering from tuberculosis. The bacillus, we may 
be fairly sure, from living it may be on food-stuffs 
outside the body, accustomed itself first to living 
on the surface and in the passages of the organism 
as a harmless saprophyte, and only later gained the 
power of living not on, but in, the tissues, and from 
that moment it became pathogenic.” So far so 
good, but then he goes on to say, this ‘“ must have 
happened centuries and centuries ago.” We may 
wonder on what evidence he comes to such a 
conclusion ; and, from my point of view, we may be 
astonished to find that he arrives at such a con- 
clusion simply because phthisis was well known to 
early Greek writers on medicine. 
In the light of the illustration that Adami had 
previously given, and of many other well-known 
facts of like kind, showing that a few days, or at 
most a week or two, will generally suffice for the 
1 Brit. Med. Journ., 1905, i. p. 1135. 
