30 Darbishire, Lmvs of Heredity. 



attain the knowledge of the result of such a combination 

 quickly and in large numbers, the random mating and 

 the counters must be discarded and one must deal experi- 

 mentally with the material, isolating the individuals the 

 properties of whose character - units one wishes to 

 determine. 



I had planned at the beginning of last year (1905), 

 to do the same experiment with peas by mating at 

 random peas with green round seeds (Eclipse) with peas 

 with yellow wrinkled seeds (British Queen), and with 

 each other ; and had already sown the seed ; when it 

 occurred to me that I need not have done so. We know* 

 the result of crossing a yellow wrinkled with a 

 green round pea, and of their mating inter se : so that all 

 that is necessary is to start with a hat containing equal 

 numbers of yellow and green counters representing pistil 

 parents, and a hat with similar contents representing 

 pollen parents, and to mate the contents at random, the 

 result of each of the 3 possible unions, ^x^.^xj'.j'Xjr, 

 being known by previous experiment. And the result of 

 the matings of the various kinds of offspring can be 

 predicted from the knowledge, which we have, of their 

 gametic constitutions. Thus, for example, in F,^ a yellow 

 resulting from the union yellow x yellowj- will produce 

 only yellow when mated with green ; but a second yellow 

 (indistinguishable by outwardly observable features from 

 the first) produced by the union yellow x green will 

 produce half yellows and half greens when mated with 

 green ; while a green of what ancestry soever will always 

 produce green when mated with green. 



Ex Jiypotliesi Mendeliano it is possible to predict the 

 result of these unions for however many generations 



* Hurst :04. 

 f These colours refer to the gametes. 



