42 DAKWmiSM chap. 



have been carefully described, so that we possess a consider- 

 able mass of information on the subject. Utilising this in- 

 formation we will now endeavour to give some idea of the 

 nature and extent of variation in the species of animals and 

 plants. 



It is very commonly objected that the widespread and 

 constant variability which is admitted to be a characteristic of 

 domesticated animals and cultivated plants is largely due to 

 the unnatural conditions of their existence, and that we have 

 no proof of any corresponding amount of variation occurring 

 in a state of nature. Wild animals and jDlants, it is said, are 

 usually stable, and when variations occur these are alleged to 

 be small in amount and to affect superficial characters only ; 

 or if larger and more important, to occur so rarely as not to 

 afford any aid in the supposed formation of new species. 



This objection, as will be shown, is utterly unfounded ; 

 but as it is one which goes to the very root of the problem, it 

 is necessary to enter at some length into the various proofs of 

 variation in a state of nature. This is the more necessary 

 because the materials collected by Mr. Darwin bearing on 

 this question have never been published, and comparatively 

 few of them have been cited in The Origin of Species ; while a 

 considerable body of facts has been made knoAvn since the 

 publication of the last edition of that work. 



Variability of the Loiver Animals. 



Among the lowest and most ancient marine organisms are 

 the Foraminifera, little masses of living jelly, apparently 

 structureless, but which secrete beautiful shelly coverings, 

 often perfectly symmetrical, as varied in form as those of the 

 mollusca and far more complicated. These have been studied 

 with great care by many eminent naturalists, and the late Dr. 

 W. B. Carpenter in his great work — the Introduction to the 

 Study of the Foraminifera — thus refers to their variability : 

 " There is not a single species of plant or animal of which the 

 range of variation has been studied by the collocation and 

 comparison of so large a number of specimens as have passed 

 under the review of Messrs. Williamson, Parker, Rupert 

 Jones, and myself in our studies of the types of this group ;" 

 and he states as the result of this extensive comparison of 



