674 ZOOLOG ¥. 
exposed to human interference may vary when subjected to 
changes in their environment. Also the fact that man can, by 
careful selection, breed races of horses adapted for draught, 
speed, or the road ; races of cows for different qualities of 
milk ; beeves for meat ; races of sheep for pre-eminence in 
the quality of their wool or mutton, or races of doves or 
poultry for beauty, usefulness, or other qualities ; the fact 
that gentleness, and generally good mental qualities, can be 
made to replace viciousness in horses, cattle, dogs—all these 
and many other facts, in the art of breeding animals known 
to fanciers, indicate that nature has, through the past ages, 
by the operation of natural laws, evolved races and species 
of animals which have followed constantly improving lines 
of development, the outcome of which are creatures the best 
fitted to withstand the struggle for existence, the most use- 
ful in the scheme of nature, and the most in harmony with 
the world about them. Progress, on the whole, therefore, 
has been beneficent, the best proof of which is the last 
product of evolution, man, the paragon of creation. 
Lamarck laid the foundations of the doctrine of evolution, the fac- 
tors he suggested being changes in the environment, inducing new needs 
and desires in animals, and consequent use and disuse of organs, aiso 
the transmission by heredity of characters acquired during the lifetime 
of the individual. But his doctrines were published, in 1809, in very 
crude shape, and before the sciences of geographical distribution, em- 
bryology, paleontology, and of histology were adequately understood 
or had even been founded. Lamarckism in its modern form is called 
Neolamarckism, It comprises the fundamental factors of evolution. 
Darwin in 1859 published the principle of natural selection and its 
general application, and supported it upon such broad grounds that it 
was universally accepted. Herbert Spencer insisted on the fact of 
“* the survival of the fittest.” Neolamarckism endeavors to explain the 
origin of variations, and thus lays the foundation on which natural 
selection rests. 
We may with some changes adopt the following tabular view by 
Giard of the factors of organic evolution: 
Direct.—Changes of cosmical environment, changes of 
climate, light, darkness, temperature, dryness aud 
humidity, physical aud chemical constitution of the 
soil and of waters, mechanical state of the milieu, 
winds, currents of water. biological environment, 
food, parasitism, symbiosis. 
Indirect.—Reaction against cosmical environmental 
conditions; adaptation, convergence, reaction against 
| biological conditions, mimicry. 
II. Secondary | Heredity, vital concurrence, natural and sexual selec- 
I. Primary 
factors. 
tion, segregation, geographical isolation, amixia, 
factors. hybridity. 
