"i] Novelties by Re-combination 71 



F 2 consists of 9 reds without cream, 3 reds with cream, 

 3 whites, i cream. 



When the allelomorphs are correctly distinguished the 

 significance of this series is obvious. The operations may 

 be shown in a tabular form, thus 



Parents .................. Red variety x Cream variety 



Allelomorphs L . R( f sa ? ^> , n , Colourless sap (R) 

 (Colourless corps. (D) 



Yellow corpuscles (R) 

 Red sap 

 (Colourless corpuscles 



P j Red sap Red sap Colourless sap Colourless sap 



2 (Colourless corps. Yellow corps. Colourless corps. Yellow corps. 



Appearance 9 Red 3 Red Cream 3 White i Cream 



These cases of novelties resulting through a re-combi- 

 nation of the factors brought in by the original pure types 

 are striking because it is not at first sight evident how the 

 novelty has been produced. Generally speaking, however, 

 the re-combinations form in F 9 a series of types many of 

 which are obviously new combinations of features which 

 could be recognized on inspection as present in the pure 

 parents. Thus the cross between a bearded, rough chaff, 

 red wheat, and a beardless, smooth chaff, white wheat give 

 in F 1 a beardless, rough chaff, red. But in F 2 all the 

 different possible combinations occur, such as bearded, 

 smooth, red ; beardless, rough, white ; bearded, rough, 

 white, &c., each in their appropriate numerical proportions. 

 In the Guinea-pig, starting from albino, smooth coat, long 

 hair, and crossing it with coloured, rough coat, short hair, 

 F 1 is coloured, rough coat, short hair. But F a contains the 

 various re-combinations of these three pairs of characters, 

 such as albino, rough coat, short hair ; coloured, smooth coat, 

 long hair, &c. Thus by selecting any desired type in F z 

 any of these new combinations can be fixed and perpetuated. 

 Basing his procedure on a knowledge of the dominance or 

 recessiveness of each character the breeder may thus guide 

 his operations with certainty. 



That this has been the mode by which most of the new 

 breeds of domesticated plants and animals have been created 

 is obvious. The traces of it remain in many cases. For 



