57 
lower animals, that he has noticed among ourselves, open up a vast field of 
inquiry, and one would like, if there were time to go through the paper, to 
follow these out in detail. The whole question is one of great interest, 
because we find that the Ethiopian type is unchangeable as represented in 
some of the early sculptures of Nineveh and in the Egyptian frescoes, and 
yet we know how very rapidly a race may change and lose its charac- 
teristics. The subject is one worthy of very careful attention. There is 
only one other point to which I would refer, and that is the curious caprices 
of disease, to which reference has been made. If we take the splenetic 
fever, mentioned in the paper as breaking out in Norfolk, we are struck with 
its curious recurrence on almost the same day in the year on each occasion. 
When we remember the experiments made by M. Pasteur, they appear 
so completely to cover the whole ground that we begin to think we know 
all about the disease, and yet, when we have read what he has to say, we still 
find that we are ignorant as to why all the cattle in England do not die of 
splenetic fever, or why any cattle die of that disease. M. Pasteur has 
shown how difficult it is to stamp out this disease, and yet it breaks 
out in this most capricious way. It is the same with regard to cholera, 
a disease belonging to hot countries ; whether it is spontaneously 
produced by those countries is a question I must leave to the learned 
to decide, but there is no doubt of its scope and extent, nor that at 
intervals it invades Europe. It has defied the efforts of all meteoro- 
logists and other scientific men to discover the exact causes which 
produce the widespread infection that again and again have decimated 
Europe in modern times, just as it did in the Middle Ages. Nor can 
any one give a reason why the Egyptian plague should have spread 
through England in the extraordinary manner in which it has again and 
again come amongst us, producing such terrible ravages. No doubt, dirt 
and bad habits have had a good deal to do with these things ; but still, 
dirt and bad habits may and do exist without the appearance of cholera or the 
Egyptian plague ; for, if these diseases be the necessary product of places as 
dirty and badly managed from a sanitary point of view as it is possible to 
be, then I think that some places I could mention ought to be constant foci 
of plague and malignant disorders. Here, therefore, I think we are met 
by an insoluble problem, and it is perhaps well for us to reflect some- 
times over these insoluble problems. (Hear, hear.) We ought not to think 
science so simple a subject, that when we have seen the beautiful unity 
which runs through the demonstrations of scientific theories we have learned 
all it is necessary to know. There is a more difficult lesson to be learnt 
still, and that is, to understand the exceptions. Until we have mastered 
them, we have only half learned our lesson. We should be crude astronomers 
if we took it for granted that the planets all moved in regular ellipses, as 
they are represented to do in the diagrams of astronomy, without studying to 
attain a knowledge of the laws by which their complex motions are governed, 
and the reason of apparent anomalies, and, in the same way that a study of 
these laws is essential to a knowledge of astronomy, so ought we to endeavour 
