152 THE POPULAR SCIENCE MONTHLY. 



of increased strength and development arising out of the habitual and healthy 

 use of special organs, and of the transmission of these to offspring — is a case 

 illustrated by many examples in the breeding of domestic animals. I do not 

 know to what else we can attribute the long slender legs and bodies of grey- 

 hounds so manifestly adapted to speed of foot, or the delicate powers of smell in 

 pointers and setters, or a dozen cases of modified structure effected by artificial 

 selection. 



In none of the assertions contained in this passage can I 

 agree. Had the inheritance of "functional and structural de- 

 cline " been " not generally disputed/' half my argument would 

 have been needless ; and had the inheritance of " increased 

 strength and development " caused by use been recognised, as 

 " illustrated by many examples/' the other half of my argument 

 would have been needless. But both are disputed ; and, if not 

 positively denied, are held to be unproved. Greyhounds and 

 pointers do not yield valid evidence, because their peculiari- 

 ties are more due to artificial selection than to any other cause. 

 It may, indeed, be doubted whether greyhounds use their legs 

 more than other dogs. Dogs of all kinds are daily in the habit 

 of running about and chasing one another at the top of their 

 speed — other dogs more frequently than greyhounds, which are 

 not much given to play. The occasions on which greyhounds 

 exercise their legs in chasing hares occupy but inconsiderable 

 spaces in their lives, and can play but small parts in developing 

 their legs. And then, how about their long heads and sharp 

 noses ? Are these developed by running ? The structure of the 

 greyhound is explicable as a result mainly of selection of vari- 

 ations occasionally arising from unknown causes ; but it is inex- 

 plicable otherwise. Still more obviously invalid is the evidence 

 said to be furnished by pointers and setters. How can these be 

 said to exercise their organs of smell more than other dogs ? 

 Do not all dogs occupy themselves in sniffing about here and 

 there all day long : tracing animals of their own kind and of 

 other kinds ? Instead of admitting that the olfactory sense is 

 more exercised in pointers and setters than in other dogs, it 

 might, contrariwise, be contended that it is exercised less ; see- 

 ing that during the greater parts of their lives they are shut up 

 in kennels where the variety of odors, on which to practise their 

 noses, is but small. Clearly if breeders of sporting dogs have 

 from early days habitually bred from those puppies of each lit- 

 ter which had the keenest noses (and it is undeniable that the 

 puppies of each litter are made different from one another, as 

 are the children in each human family, by unknown combina- 

 tions of causes), then the existence of such remarkable powers 

 in pointers and setters may be accounted for ; while it is other- 

 wise unaccountable. Th^se instances, and many others such, I 



