22 
Address of the President. 
the aspect under which the questions at issue present them- 
selves to mj own mind, as to lead jou to a conception of 
the mode in which (as it appears to me) their solution is to 
be sought for. That I have myself fully attained that solution 
I dare not affirm. That the principle I offer to you, however, 
is more consistent with known facts, than are the doctrines 
commonly entertained, I feel a very strong conviction. 
Although the general organization of Plants was so far 
understood at the time when Schleiden first came before the 
public, that every vegetable tissue was recognised as essen- 
tially cellular in its nature, yet I consider it to have been by 
him that the fundamental truth was first broadly enunciated, 
in 1837, that, as there are many among the lowest orders of 
plants in which a single cell constitutes the entire individual, 
each living /or and bj/ itself alone, so each of the cells, by the 
aggregation of which any individual among the higher plants 
is formed, has an independent life of its own, besides the 
' incidental ' life which it possesses as a part of the organism 
at large ; and that the doctrine was first proclaimed, that the 
life-history of the individual cell is, therefore, the very first 
and absolutely-indispensable basis, not only for Vegetable 
Physiology, but (as was even then foreseen by his far reach- 
ing mental vision) for the science of life in general. The 
first problem which he set himself to investigate, therefore, 
was, hoiu does the cell itself originate'? It is unfortunate that 
he should have had recourse for its solution to some of those 
cases in which the investigation is attended with peculiar 
difficulty ; and it is, doubtless, in great part to this cause, that 
we are to attribute certain fallacies in his results, of which 
subsequent researches have furnished the correction. 
The publication of the ' Microscopical Researches' of 
Schwann, in 1839, marks a like era in Animal Physiology. 
For although the doctrine could not be said to be a new one, 
that each integral part of the animal body possesses an inde- 
pendent life of its own, in virtue of which it performs a 
series of actions peculiar to itself, provided that the condi- 
tions of these actions be supplied, yet it derived a new 
significance from the idea with which he connected it, that 
the integral parts are either cells or derivatives from cells^ and 
that their independent life is, therefore, cell-life. This idea, 
avowedly suggested by that of Schleiden, was based by 
Schwann on the apparently-satisfactory results of his micro- 
scopic observations on the development of the animal tissues. 
For he found, that however diverse may be the structure and 
actions of the component parts of the animal organism in 
their fully-developed condition, there is a period in its 
