VARIATION. 269 



become what they are, and what are the forces which govern 

 them?" 



Darwin, no doubt, gave us the first hope of a solution in the 

 production of his ' Origin of Species ' : "No character of Form is 

 common to all things." On the contrary, Form is infinitely 

 diverse. 



The existence among living creatures of a specific difference 

 is a characteristic of Life, and to these phenomena of the occur- 

 rence of differences between the structure, the instincts or other 

 elements which constitute the individual, the term " Variation " 

 has been given. The importance of Variation is clearly shown 

 by the fact that it is upon these phenomena that all theories of 

 Evolution are based. 



It is unnecessary to enter into the theory of the ' Doctrine of 

 Descent,' which states that all living beings are genetically linked, 

 unless the alternative theory is held, namely, that separate 

 creations were resorted to, which theory is now held to be 

 absurd, but still, although the balance of evidence is in its favour, 

 we must bear in mind that it is as yet to a great extent .an 

 assumption, and that it is adopted as a working postulate. 



Lamarck, as will be remembered, regarded organisms as 

 machines, which have the power of adaptation as an inherent 

 quality in them. Therefore, as the world changes, so does the 

 individual — that is, the universe and the individual change pari 

 passu. This is Lamarck's explanation of the occurrence of Varia- 

 tion. Darwin, on the other hand, acknowledges the presence of 

 Variation, but does not suggest emphatically any cause for its 

 presence, because he found that some of the Variations were not 

 adaptations, but quite the contrary. 



The readiest way, and one which is being universally adopted, 

 of solving the problem of Variation is to study the facts of 

 Variation. This is done in two ways : — 



(1) Embryologically. 



(2) By the study of adaptation as shown in the organism. 

 The first has as yet given little light upon the subject ; the 

 second much more. 



Getting now to the subject of Variation as exhibited by 

 earthworms, so far as examination has gone, Bateson, in his 

 valuable book, 'Materials for the Study of Variation,' states 



