782 
PROCEEDINGS OE SECTION I. 
Now, first I must remind you, however tempting and probable the 
analogy may seem, that we know nothing whatever of corresponding 
facts concerning the B. lepras. We do not in the least know whether it is 
an endogen or an ectogen. But, beyond that, we have seen that leprosy 
is communicated by the direct channel (if at all) with great difficulty. 
Whatever the reason may be. that seems to be the fact. That being 
so, I do not understand whv it should be supposed to be more easily 
communicable by an indirect channel. If, nevertheless, it demon- 
strably were so (but there is no better evidence of indirect thau of 
direct communication within households) the explanation would surely 
lie in the B. lepra being an ectogen, and in its return to the earth or 
to some habitat outside man being a condition of the easy infection 
of fresh persons. It may be that indirectness of the channel was 
not supposed to enhance communicability, but merely to facilitate 
communication by bringing the virus into contact with a larger 
number of persons, and affording it, consequently, a freer oppor- 
tunity of encountering the few among them who were susceptible. 
In that case imported lepers ought to establish new leprosy areas. 
This point requires examination at some length. It is crucial for any 
mode of communicability, and for my own part I do not think the 
facts support it. 
Wc know perfectly well that imported lepers do not always 
create a new area of endemicity (if they ever do so), as they ought 
on the hypothesis of direct or indirect communicability. The case 
of the Norwegian lepers in the States is one in point ; that of lepers 
returned to the cities of Europe is another. I refer again to these 
two examples because the facts concerning them are perfectly well 
established, and especially because the fact that these areas are not 
areas of endemicity is ascertained. 1 know you would have no 
difficulty in culling from books many round statements that such- 
and-such areas were contaminated by imported lepers, aud were, in 
consequence, newly made areas of endemicity. Now, you will 
observe, no doubt, that if these assertions were substantial, if they 
were warranted by perfectly clear evidence, the whole question of the 
aetiology of lepra would be thereby settled once for all, and in the 
least disputable way. It would be proved thereby that leprosy was 
maintained by communication with the sick, and whether the mode 
were direct or indirect would become a secondary question and, for 
preventive purposes, no verv important one. I lay stress, therefore, 
on the counter- statement which I am about to make. It is this: In 
none of the cases of alleged importation of leprosy which thus far I 
have studied have I been able to find anything that could reasonably 
be regarded as evidence of the assertion, vital though it obviously is. 
,The datum, without which the whole case must fall to the ground, 
never is ascertained — namely, the freedom of the dwellers on the area 
under examination up to the date of the known importation of lepers* 
7 The island of Madeira was uninhabited until it was occupied by Portuga in 
1419. Emigrants from that country were introduced, many criminals and persons 
of the outcast class among them. Leprosy was then present in Portugal, as it was 
over the rest of Christendom. There is, therefore, every probability that lepers 
were to be found among the original settlers and later mum grants. Towards the 
end of the 15th century a lazaret wag established on the island, which still exists, 
and from that date lepers have been present among the population. (Goldschmidt, 
op. cit. infra.) Viewed by itself this instance affords the best presumptive evidence— 
that is, the most certainly established in point of circumstances— with which I am 
