.[2]

[Footnote 2: It has been suggested to me that these words may be taken to
imply a discouragement on my part of any sort of scientific instruction
which does not give an acquaintance with the facts at first hand. But
this is not my meaning. The ideal of scientific teaching is, no doubt, a
system by which the scholar sees every fact for himself, and the teacher
supplies only the explanations. Circumstances, however, do not often
allow of the attainment of that ideal, and we must put up with the next
best system--one in which the scholar takes a good deal on trust from a
teacher, who, knowing the facts by his own knowledge, can describe them
with so much vividness as to enable his audience to form competent ideas
concerning them. The system which I repudiate is that which allows
teachers who have not come into direct contact with the leading facts of
a science to pass their second-hand information on. The scientific virus,
like vaccine lymph, if passed through too long a succession of organisms,
will lose all its effect in protecting the young against the intellectual
epidemics to which they are exposed.

[The remarks on p. 222 applied to the Natural History Collection of the
British Museum in 1861. The visitor to the Natural History Museum in 1894
need go no further than the Great Hall to see the realisation of my hopes
by the present Director.]]

VIII

BIOGENESIS AND ABIOGENESIS

(THE PRESIDENTIAL ADDRESS TO THE BRITISH ASSOCIATION FOR THE ADVANCEMENT
OF SCIENCE FOR 1870)

It has long been the custom for the newly installed President of the
British Association for the Advancement of Science to take advantage of
the elevation of the position in which the suffrages of his colleagues
had, for the time, placed him, and, casting his eyes around the horizon
of the scientific world, to report to them what could be seen from his
watch-tower; in what directions the multitudinous divisions of the noble
army of the improvers of natural knowledge were marching; what important
strongholds of the great enemy of us all, ignorance, had been recently
captured; and, also, with due impartiality, to mark where the advanced
posts of science had been driven in, or a long-continued siege had made
no progress.

I propose to endeavour to follow this ancient precedent, in a manner
suited to the limitations of my knowledge and of my capacity. I shall not
presume to attempt a panoramic survey of the world of science, nor even
t