1897.] A Chapter in the History of Science. 859 
ies.” Some of these may be considered as mere coincidences; 
others provoke skepticism for one reason or other. To discuss 
them would be out of place here. But at least we may meet 
evidence with counter-evidence. 
On the one hand, all the data and experiments recapitula- 
ted in the cases enumerated concern only two, or, at most, very 
few, generations of the animals in question, and were within 
the compass of a single man’s life-time. 
On the other hand, we have data and observations of the 
most reliable nature, and of an extraordinary compass. These 
have resulted not from experiments for the determination of a 
specific question, but from observances of a religious character. 
They were really in the nature of surgical operations, but for 
our purpose may be looked upon as experiments, and have the 
value of contrived experiments. In no other field has such a 
series of disinterested experiments been available. They were 
conducted on countless millions of mankind and for thousands 
of years. The subjects experimented upon were kept isolated 
from others alike by their own prejudices and the prejudices 
of their neighbors. Circumcision is the term applied to the 
experiments in question. 
For about 4,000 years circumcision has been practiced on a 
gigantic scale. Every male child among the Jews was opera- 
ted upon, not only in Palestine, but wherever representatives 
of the race had wandered and adhered to their religion ; reli- 
gion itself was involved in the operation and it was regarded 
as a holy rite; the most scrupulous attention was paid to de- 
tails. The operation was performed eight days after birth, 
and consequently there could be no functional activity of the 
tissues concerned. But after 4,000 years the new-born boys of 
the race come into the world with the special integument de- 
veloped as much as in those of other races. Even the princi- 
ciple of atrophy through disuse has not become manifest in the 
case. 
Other evidence, it seems to me, is the result of confounding 
the potentiality of a function with its manifestation. I allude 
to one set of examples on account of the interest of the cases, 
and I do so with the deference due to the eminence and abil- 
