128 



GENETICS 



below, very nearly to the 'expected theoretical ratio 

 of 3 to 1. 



Darbyshire repeated the yellow-green cross with 

 garden peas, obtaining in the second generation the 

 large total of 139,837 individuals of which 105,045 

 were yellow and 34,792 green, which is very close to 

 3 to 1. 



5. SOME FURTHER INSTANCES OF "MENDEL'S 

 LAW" 



Since the rediscovery of Mendel's law the ratio of 

 3 to 1 in the second generation has been found by 

 a number of different investigators to be constant in 

 a large array of characters observed both in animals 

 and plants of diverse kinds when these are cross-bred 

 with reference to the characters in question. 



Botanists have the advantage perhaps in this 

 matter, as they deal with forms which usually produce 

 a large number of offspring from a single cross, 

 a very desirable thing in estimating ratios. On the 



