Claypole.] 1-^" [April 1, 



variates. We have but to admit that the changes which occurred to the 

 earlier variable organism were attended with little or no advantage, and 

 that consequently the variable shows no diminution or tendency to extinc- 

 tion by the side of its more specialized variate offspring and the difficulty 

 entirely disappears. 



"We are compelled to admit variation of all degrees ranging from that 

 which rapidly kills off through that which is absolutely neutral to that 

 which puts its variates at so great an advantage above their fellows that 

 they soon leave them behind and become the " Winners in Life's Race." 



VI. 

 The Cause of Variation. 



For a variation so wide in its range as that above described a cause 

 equally wide must be sought. JSio narrow or arbitrary limits can be set 

 to the cause of a universal consequence. And what more natural or more 

 obvious cause can be suggested than the changes constantly occurring in 

 the environment of the organism ? This is of course not a new suggestion, 

 but some writers on evolution seem afraid to carry it out to its full extent. 

 They seem unwilling to abandon the organism to the uncontrolled, con- 

 fused and seething waves of the sea of physical nature. Yet only in the 

 ceaseless, never repeated tossing of this unresting sea can be found a 

 cause at once sufficiently changeful and far reaching to correspond with 

 the observed changes of the organisms that are borne upon its surface or 

 that live among its waters. Elsewhere in vain do we look for any means 

 of explaining them. All other known natural causes are insufficient and 

 to resort in a difficulty to the unknown and the supernatural is to place 

 the enquiry beyond the pale of science. 



In the changes of the physical world therefore and in these alone do we 

 find a cause even presumably sufficient to account for the continual and 

 contemporaneous changes in organic beings. It would be idle to assert 

 that we know the precise mode of action in which the former produces 

 the latter. So new and unexplored is this field that such knowledge is at 

 present impossible. But with every advance we see more and more prob- 

 ability that in the one we have the real and efficient cause of the other. 

 Experiments on the influence of food, temperature, light and other phys- 

 ical agents upon the modification of organisms especially during the 

 formative part of their existence are gradually giving us a mass of infor- 

 mation which has already greatly modified former opinions. Some forms 

 once ranked as distinct varieties or even species are now known to be 

 mere accidents resulting from the conditions in which part of their pre- 

 vious existence was spent. Especially is this true with regard to the 

 lower forms. 



Time and space will not allow many quotations. One or two must 

 suffice. 



"The Mexican axolotl is a tadpole-like animal of considerable size 

 which lives in the water, breathes by gills and is reproduced from eggs. 



