RECENT DISCOVERIES IN HEREDITY. 203 



One large class was like the parents, short-haired, rough and pig- 

 mented. Two other classes were like the grand-parents, viz, short- 

 haired smooth pigmented, and long-haired rough albino. In addition, 

 there were five other new classes not represented among the parents or 

 grandparents. These were: short-haired rough albino (Fig. 11), 

 short-haired smooth albino (Fig. 9), long-haired smooth albino (Fig. 

 7), long-haired smooth pigmented (Fig. 10), and long-haired rough 

 pigmented (Fig. 12). 



The eight classes of young produced in this experiment are not all 

 equally numerous. The largest class is that which contains the three 

 dominant characters (Fig. 6), the smallest that which contains the 



Fig. 11. A Short-haired, Rough, Albino Guinea-pig. 



three recessive characters ( Fig. 7 ) . Theoretically, they should number 

 27 individuals and 1 individual, respectively, in a total of 6-1 young. 

 These proportions are roughly approximated in the observed result. 



This experiment illustrates two important principles in heredity : 

 First, if as regards the hair alone there exists such a variety of char- 

 acters separately heritable, 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 1 alternative conditions. Secondly, the experiment 

 shows how a variety of new organic forms may quickly be pro- 

 duced by cross-breeding, leading to the combination in one race of 

 characters previously found separately in different races. Thus, in 



