224 



CAUSES OF VARIATION 



seen a respectable development of fat when the sheep were kept 

 under ordinary conditions. 



One of the most remarkable and seemingly best authenticated 

 instances of the evil influence of locality upon character devel- 

 opment is the almost uniform failure to maintain the quality of 

 certain English breeds of dogs when bred in India. We are 

 indebted again to Darwin 1 for the remarkable statement that in 

 that country the bulldog rapidly loses his ferocity, and of all 

 dogs the hounds decline most rapidly. 



Instances might be multiplied indefinitely, but two things 

 must be borne in mind by the student when dealing with this 

 class of facts : first, there is the greatest opportunity for error 

 or exaggeration from inexact observation and report ; second, 

 the plant or animal is exposed to a multitude of new conditions 

 when transplanted to a new locality, only a portion of which are 

 inherent in the conditions of life. Commonly the breeders or 

 attendants are not familiar with the new form and do not afford 

 proper conditions, as in not giving suitable food to animals or 

 in failing to afford sufficient room to large-growing varieties 

 of plants. 2 



After making due allowance, however, for all these considera- 

 tions, the fact remains that the conditions of life evidently do 

 exert a strongly modifying influence upon development. 



Locality a comprehensive term. There is little use in attempt- 

 ing to determine the exact influence of each separate locality. 

 The term is an exceedingly comprehensive one, including many 

 things, climate, by which we mean not only temperature, 

 moisture, and light, but their comparative proportions in that 

 particular spot ; season, by which we mean the succession of 

 climatic conditions ; food (both as to quantity and quality), on 

 which the creature absolutely depends, not only for life but also 

 for growth ; habits of life, radical changes in which may be forced 

 upon the animal by its habitat. 



This is all too complex for profitable study anji discussion. 

 We must separate locality into its elements and determine, if we 



1 Darwin, Animals and Plants, I, 39. 



2 It will be noted in this connection that most of the instances cited are those 

 of deterioration. 



