4 
mere collection of cabinet curiosities, whose individual worth was 
estimated by comparative rarity or singularity of form, whilst the 
more important facts in regard to the relation of animal, vegetable, 
and mineral bodies, the one to the other, were entirely overlooked. 
In recent times, however, the votaries of science, by tracing out 
the intermutual relations and the reciprocal influences which these 
bodies directly and indirectly exert upon one another, have fairly 
realised the existence of a fundamental unity of plan pervading all 
created nature throughout time and space. I believe, indeed, with 
respect to this planet, that it is not too much to affirm, that in all 
epochs of the earth’s history — in whatever phase its cosmical ele- 
ments have appeared — the laws prevailing hitherto are the same 
as those in operation at the present day ; whilst the singularly 
varied results which we now witness are regulated by the degree , 
direction , and conditional circumstances under which those laws 
are permitted to exercise their sway. To demonstrate the truth of 
this persuasion in its entirety is not my present concern ; yet, I 
have not hazarded this generalization without careful, prolonged, 
and independent reflection. 
Were it now my intention to develop the legitimacy of this hy- 
pothesis, it would be necessary — in order to give full effect to its 
claims — to furnish illustrations too numerous and varied for a 
single discourse. I will endeavour, nevertheless, to throw a ray of 
light on the matter. 
As far as the mere toil of observation goes, whether natural or 
artificial, the Naturalist may be compared to an Astronomer, whose 
investigations embrace so vast a region, that in proportion as his 
examinations become minute, so do the limits of his study recede, 
appearing more and more distant and immeasurable. 
Whatever section, or segment of the circle of the known, engages 
his immediate attention— and the same thing holds good if we 
suppose him to be acquainted with all the results which the com- 
bined experience of his fellow-workers has produced — whatever 
department of the known, I repeat, is occupied, the regions un- 
explored must necessarily enclose oceans of truth for ever hidden 
from his gaze. 
Reflecting on such a consideration as this, I can readily imagine 
that some such a question as the following may occur to you, and 
I shall suppose that you put it to me thus : “ If, as you aver, the 
known bears so insignificant a proportion to the unknown, might 
not a more extended acquaintance with those unexplored regions — 
assuming it possible to acquire this knowledge — produce facts or 
phenomena the study of which, if submitted to the ordinary in- 
ductive tests, would be sufficient to weaken or altogether overthrow 
your generalization?” 
To this I confidently answer, — Certainly not ! 
Let us, if you please, look more closely to the position of the 
Naturalist — or say, rather, the Biologist. 
