452 TROPICAL NATURE 1x 
anatomy could be applied to the classification of animals 
according to their whole organisation in a far more natural 
manner than by the easier method of Linneus. Later on, 
when improved microscopes and refined optical and chemical 
tests became available, the study of anatomy was carried 
beyond the knowledge of the parts and organs of the body— 
such as bones, muscles, blood-vessels, and nerves—to the 
investigation of the tissues, fibres, and cells of which these 
are composed ; while the physiologists devoted themselves to 
an inquiry into the mode of action of this complex machinery, 
so as to discover the use of every part, the nature of its 
functions in health and disease, and, as far as possible, the 
nature of the forces which kept them all in action. 
Down to the middle of the present century the study of 
nature advanced with giant strides along these separate lines 
of research, while the vastness and complexity of the subject 
led to a constantly increasing specialisation and division of 
labour among naturalists, the result being that each group of 
inquirers came to look upon fis own department as more or 
less independent of all the others, each seemed to think that 
any addition to his body of facts was an end in itself, and that 
any bearing these facts might have on other branches of the 
study or on the various speculations as to the “system of 
nature” or the ‘true method of classification” that had at 
various times been put forth was an altogether subordinate 
and unimportant matter. And, in fact, they could hardly 
think otherwise. For, while there was much talk of the 
“unity of nature,” a dogma pervaded the whole scientific: 
world which rendered hopeless any attempt to discover this 
supposed unity amid the endless diversity of organic forms 
and structures, while so much of it as might be detected 
would necessarily be speculative and unfruitful. This dogma 
was that of the original diversity and permanent stability of 
species, a dogma which the rising generation of naturalists 
must find it hard to believe was actually held, almost 
universally, by the great men they look up to as masters in 
their several departments, and held for the most part with 
an unreasoning tenacity and scornful arrogance more suited 
to politicians or theologians than to men of science. Although 
the doctrine of the special and independent creation of every 
