114 J. B. CLELAND. 
have also seen them in the same situation in a N.S.W. pig 
(October, 1911), and also in a growth of a pig’s foot. They 
are also found in intestinal lesions in these animals. They 
may be found in several species of our white ants (Ter- 
mites) and in mollusca. 
From the above it will appear that Spirochetes, in the 
broad sense, are widely distributed organisms found in 
many Situations in association with various animals. In the 
above instances they seem, for the most part, to be simple 
saprophytes, living on mucous and allied surfaces, and 
deriving nourishment, presumably, from the broken down 
organic material there found in abundance. In some of 
the cases mentioned above, however, it is possible that they 
may also exert some pathogenic action—that is to say, they 
may feed upon the living tissue or may utilise foodstuffs in 
course of passage to the host’s cells. As a result of such 
damage or interference, or as a result of the production of 
toxins, they may cause a reaction to their presence by the 
cells of the host. The skin ulcers of pigs and perhaps the 
castration tumours may be such instances. We also find 
from time to time in man that certain spirochetes of the 
mouth may be present in large numbers in particular ul- 
cerations and infections of that region and the neck, con- 
stituting Vincent’s angina. 
Some of these saprophytic-living spirochetes, then, ap- 
pear to possess potentialities for pathogenic activity, if 
given the opportunity. The opportunity may be perhaps 
a wound or other infection. In such spirochetes, in fact, 
we see the beginning of the evolution of true parasites with 
pathogenic powers. To my mind it is unquestionable that 
the organism of syphilis, the dreaded Sp. pallida, has 
evolved from a saprophyte inhabiting originally only the 
mucous surfaces of the vagina and prepuce. Promiscuous 
sexual intercourse gave such saprophyte its chance to estab- 
