314 GENERAL BIOLOGY 



lished by its founder, is represented in the accompanying 

 table (after Castle) . 



Castle has proved by breeding experiments that in guinea 

 pigs length, pigmentation and roughness of coat are hair 

 characters that are separately heritable, and that in crossing 

 they follow fairly Mendel's law. And he summarizes his 

 observations as follows: 



"This experiment illustrates two important principles in 

 heredity: First, if as regards the hair alone there exists 

 such a variety of characters separately inheritable, how 

 great must be the number of such characters in the body as 

 a whole, and how remote the probability that any animal 

 will in all characters resemble any individual ancestor, pro- 

 vided that in a considerable number of heritable characters 

 a choice is offered between alternative conditions. Secondly, 

 the experiment shows how a variety of new organic forms 

 may quickly be produced by cross-breeding, leading to the 

 combination in one race of characters previously found 

 separately in different races. Thus,, in guinea-pigs, one can 

 obtain within two generations any desired combination of 

 the three pairs of alternative coat-characters, if one pro- 

 duces a sufficiently -large number of individuals. 



