IS LEPROSY A TELLURIC DISEASE ? 
785 
that the density is uncommonly high, or 170 to the square kilometre. 
The author said — and observe that he was not dealing with a matter of 
ancient history, but was giving the result of his personal experience 
during the past twenty-six years — that it might be taken that two-thirds 
of the close-packed population, or about 80,000 of the people, lived 
in la inhere (a scarcely translatable term which means, on the whole, 
incessant labour rewarded by earnings which scarcely suffice to provide 
food adequate to the labourer’s physiological expenditure), and that 
the state of the people was still going from bad to worse. Hence, if 
leprosy were maintained by direct communication with the sick, or by 
indirect communication, or if natural resistance to leprosy in particular 
could be impaired by a lifetime led in la misere , or if loss of natural 
resistance were indeed the determining cause of the endemic persistence 
of leprosy, then Madeira, at all events ought to be ravaged by this 
disease. But what is the fact ? The author reckoned but seventy 
cases in the whole island. 
Thus I consider that the epidemiological facts no more support 
the theory of indirect communication than they support the simpler 
hypothesis of direct communication. This seems to me to be clear, 
but on the all-important condition that facts alone shall be allowed 
weight, and that guesses and assumptions shall be recognised and 
discarded. On the other hand, the character of leprosy, as deduced 
from a general survey of its behaviour the world over, is that of an 
endemic disease — of a disease which is essentially connected with 
locality. If a man visit a recognised leprosy area he runs an 
appreciable chance of contracting leprosy ; but if a leper go to 
Europe his neighbours seem to be in no more danger of leprosy than 
they were before he returned among them. 
If we confine ourselves to a pathological view, many of us will 
feel inclined to say that probable analogies class the B. leprae with the 
endogens.* But, to the extent of my researches, the epidemiological 
facts seem to me to point to its being an ectogen ; and not merely 
such an ectogen as the cholera vibrio, but rather such as is the bacillus 
of tetanus. Nor need it be supposed that on this view leprosy should 
be much more common than it is, even on areas of its endemicity. 
The defensive function is not to be undervalued. It may well be that 
our phagocytes are usually victorious over that ancient enemy, the 
B. leprce. But beyond that we now know, thanks to the labours of 
M. Metschnikoff (choleraf) and MM, Yailiard, Vincent, and Kouget 
(tetanusj), that successful infection is not always due to weakening 
of the defensive function by agents which are ‘‘depressant” in general 
terms. Men do not acquire tetanus, for instance, merely because they 
happen to be out of health when they receive the virus ; clinically no 
fact is better known than that, I suppose. Nor do those who drink 
too much beer or eat too much fruit during a cholera epidemic 
succumb to cholera merely because they have become generally 
depressed by drunkenness or by diarrhoea. No ; it is the concurrence 
with the B. tetani and the Vibrio cholerce of other organisms— quite 
* Cf. E. Klein, Pathology of the Infectious Diseases in “A Treatise on Hygiene, 
edited by Stevenson and Murphy, 1893. 
f Ann. Inst. Pasteur, 1893-4. 
X Ibidem, 1891-2-3. 
