302 The Field Naturalist's Quarterly November 



systematist gives expression to these variations by dividing 

 animals into orders, families, genera, and species, according 

 to their affinities and differences, thus emphasising the fact 

 that some animals are closely related to others. But, further 

 than that, it is a matter of common knowledge that no two 

 animals are exactly alike, even the members of the same 

 litter, except under very exceptional circumstances which we 

 need not consider. Out of a litter of half a dozen puppies, 

 some may resemble one parent, some another, some neither ; 

 while as they grow up to adult life entirely new characters 

 may make their appearance in one of them. In other words, 

 there is great variation even in closely related organisms. 

 It is the question of what causes this variation in animals 

 that gave rise to the two views above mentioned. How came 

 the wonderful variety in shape, size, structure, and habits 

 of all the species of animals ? A paragraph in Mr. G. P. 

 Mudge's Text-Book of Zoology puts the matter as follows : — 

 " Biologists are divided into two great camps on the 

 question of the ' Origin of Species.' There is the Lamarck- 

 ian or older camp, and the Darwinian or newer one. 

 The former asserts that organisms are profoundly modified 

 by the necessities of their existence and the nature of their 

 physical environment, and that these modifications are 

 hereditarily transmitted, accumulated, and perfected with 

 each generation. The Darwinian camp, on the other hand, 

 asserts that variations are fortuitous, that they arise spon- 

 taneously from some inherent cause of which we know 

 nothing, but that having arisen, they can be either advan- 

 tageous or otherwise to the organism. If advantageous, 

 then they confer a benefit and advantage upon the organ- 

 ism possessing them, which the others do not possess ; and 

 that therefore in the struggle for existence the former will 

 survive and procreate their species, and the latter will 

 become exterminated. Thus Nature selects the fittest to 

 survive and rejects the unfit, and hence to the Darwinian 

 theory has been given the name of Natural Selection. 

 Thus may be explained why organisms are adapted to 

 their environment ; not because, as the Lamarckians assert, 

 Nature has indiscriminately moulded them to it, but be- 

 cause those not so adapted have become exterminated," 



