4 BIOLOGY AND ITS MAKERS 
Asa result of these advances, animal organization began 
to have a different meaning to the more discerning naturalists, 
those whose discoveries began to influence the trend of 
thought, and finally, the idea which had been so often pre- 
viously expressed became a settled conviction, that all the 
higher forms of life are derived from simpler ones by a gradual 
process of modification. 
Besides great progress in biology, the nineteenth century 
was remarkable for similar advances in physics and chem- 
istry. Although these subjects purport to deal with inorganic 
or lifeless nature, they touch biology in an intimate way. 
The vital processes which take place in all animals and plants 
have been shown to be physico-chemical, and, as a conse- 
quence, one must go to both physics and chemistry in order 
to understand them. The study of organic chemistry in late 
years has greatly influenced biology; not only have living 
products been analyzed, but some of them have already been 
constructed in the chemical laboratory. The formation of 
living matter through chemical means is still far from the 
thought of most chemists, but very complex organic com- 
pounds, which were formerly known only as the result of 
the action of life, have been produced, and the possibilities 
of further advances in that direction are very alluring. It 
thus appears that the discoveries in various fields have 
worked together for a better comprehension of nature. 
The Domain of Biology.—The history of the transforma- 
tion of opinion in reference to living organisms is an inter- 
esting part of the story of intellectual development. The 
central subject that embraces it all is biology. This is one 
of the fundamental sciences, since it embraces all questions 
relating to life in its different phases and manifestations. 
Everything pertaining to the structure, the development, and 
the evolution of living organisms, as well as to their physiol- 
ogy, belongs to biology. It is now of commanding impor- 
