1868. ] Biology. 527 
plant, that the sap not only ascends by the vascular tissue of plants, 
but that the same tissue returns and distributes the sap after it 
has been modified in the leaves. 
After making some observations on the morphology of leaves, 
and on the subject of free-cell formation, the President referred to 
Darwin’s theory of Pangenesis. Others, he said, as Owen and 
Herbert Spencer, had broached something of the kind, but not to 
such an extent, for Darwin’s theory included Atavism, Reversion, 
and Inheritance, and embraced mental peculiarities as well as 
physical. The whole matter was at once so complicated, and the 
theory so startling, that the mind at first naturally shrank from 
the reception of so bold a statement. Like everything, however, 
which came from the pen of a writer whom he had no hesitation, 
as far as his judgment went, in regarding as by far the greatest 
observer of the age, whatever might be thought of his theories 
when carried out to their extreme results, the subject demanded a 
careful and impartial consideration. Like the doctrine of natural 
selection, it was sure to modify more or less their modes of thought. 
Even supposing the theory unsound, it was to be observed, as 
Whewell remarked, as quoted by their author, “ Hypotheses may 
often be of service to science when they involve a certain portion of 
incompleteness and even of error.” Mr. Darwin said himself that 
he had not made histology an especial branch of study, and he 
(Mr. Berkeley) had, therefore, less hesitation in expressing an 
individual opinion that he had laid too much stress on free-cell 
formation, which was rather the exception than the rule. Assum- 
ing the general truth of the theory that molecules endowed with 
certain attributes were cast off by the component cells, of such in- 
finitesimal minuteness as to be capable of circulating with the 
fluids, and in the end to be present in the unimpregnated embryo 
cell and spermatozoid, capable either of lying dormant and inactive 
for a time, or, when present in sufficient potency, of producing 
certain definite effects,—it seemed far more probable that they 
should be capable, under favourable circumstances, of exercising an 
influence analogous to that which is exercised by the contents of 
the pollen tube or spermatozoid on the embryo sac, than that these 
particles should be themselves developed into cells; and under 
some such modification the theory was far more likely to meet with 
anything like a general acceptation. Be this as it might, its com- 
prehensiveness would still remain the same. They must still take 
it as a compendium of an enormous mass of facts, comprised in the 
most marvellous manner within an extremely narrow compass. In 
conclusion, he said it was obvious how open such a theory was to 
the charge of materialism. It was an undoubted fact, however, 
that mental peculiarities and endowments, together with mere 
habits, were handed down and subject to the same laws of rever- 
VOL. V. 20 
