PROBLEMS OF DISTRIBUTION AND THEIR SOLUTION. 131 



research. This fourth query is that which demands to know " how 

 the living being has come to be what it now is" or "how it has 

 attained to its present place and position in the animal or plant 

 series." The mere terms of such a question presuppose that the 

 living population of our globe has undergone progressive develop- 

 ment. It postulates change and alteration as natural conditions of 

 existence, and it inquires how, in the case of each animal or plant, 

 such change has operated in what direction it has sped, and how it 

 has affected and modified the living organism. Thus stated, there 

 can be no difficulty in recognising the theory of evolution or develop- 

 ment as that which purports to supply this mental demand, and to 

 reply to the inquiry concerning the past history of animals and plants 

 in relation to their present position and genealogical connections. 

 Time was when the need for such a question was non-existent. So 

 long as mankind regarded the world of life as presenting a fixity of 

 constitution, there could exist no question of wide organic change for 

 the biologist to meet and answer. With a firm and undisturbed 

 belief in the special and independent "creation" of each species of 

 living beings, the mind could experience no philosophic or other 

 necessity for any inquiry into a past of modification and change. 

 Possessing the idea that stability of organisation and form was the 

 rule of existence, men had not learned to look for a past wherein, as 

 in a glass darkly, might be discerned the birth of new species arising 

 through the modification of the old. But the germ idea of such an 

 evolution of life existed and prevailed long before the age which has 

 seen its full fruition. Here and there evidence is to be found that 

 even in classic ages, the great problem of problems concerning the 

 how and why of the universe itself was growing apace in the minds 

 of men. Aristotle, remarking that rain falls not to make the corn 

 grow, any more than it descends to spoil the crops, asks, " What there- 

 fore hinders the different parts (of the body) from having this merely 

 accidental relation in nature?" So also Lucretius, in another depart- 

 ment of inquiry, shadowed forth the atomic constitution of things, 

 and paved the way for the thoughts of the after ages, when Lamarck, 

 Erasmus Darwin, Goethe, and, in our own day, Charles Darwin, 

 Wallace, and others, have busied themselves with the problems of 

 the development of the teeming population of the globe. Thus 

 arises the philosophic necessity for a fourth question that of 

 the atiology or causation of living beings. This question, utilising 

 all the knowledge gained by the sciences of structure, physiology, 

 and distribution, endeavours to show how the organic world has 

 grown and progressed towards the perfection it exhibits before our 

 waiting eyes to-day. 



This brief sketch of the four great questions of biology may 

 serve to show the exact position which the study of Distribution 



K 2 



