WHITE— STUDIES OF INHERITANCE IN PISUM. 497 



have been discovered however, which uhimately may lead to un- 

 dreamed practical possibilities. 



Heredity Studies on Pisuin Prior to 1900. 



According to Darwin (22), as early as 1729, white- (yellow 

 cotyledons) and blue- (green cotyledons) seeded varieties of peas 

 had been observed (probably through insect crossing) to give rise 

 to pods containing both blue (green) and white (yellow) peas. In 

 1787 Andrew Knight (50) had crossed various races of peas and 

 originated many new varieties, some of which, e. g., Knight's Tall 

 Wrinkled Marrow, are said (42, 'J2) to have persisted in a prac- 

 tically unmodified form, but under difit'erent names (British Queen), 

 down to the present day, representing, if true, a striking illustration 

 of the constancy of an old variety, through a hundred years or 

 more of inbreeding. Knight, in many ways, was a forerunner of 

 Mendel, as he had observed the dominance of tallness in peas over 

 dwarfness, purple flower color over white flower color, gray brown 

 seed coats over uncolored seed coats and the breeding true of re- 

 cessives and part of the dominants. But he was unaware of the 

 significance of these facts and of the importance of determining the 

 ratios of the various kinds in the second and third hybrid genera- 

 tions. He is credited, however, by Sherwood (72) with having 

 given us the start in wrinkled seeded varieties of peas, as before 

 his time wrinkled peas appear to have been unknown. 



Goss in 1822 (36, 21) also anticipated Mendel by his observa- 

 tions on the cotyledon colors of peas, i. e., the dominance of yellow 

 over green cotyledons in the first hybrid generation and the occur- 

 rence of green and yellow peas in the same pods in the second 

 hybrid generation, as well as the subsequent breeding true of part 

 of the yellow seeds and all of the green seeds in later generations. 

 Appended to Goss's description of his results is an editorial com- 

 ment giving the results of crossing green and white (yellow) peas 

 by one, Mr. Seton. Seton used the green-seeded Dwarf Imperial 

 as the maternal parent in a cross with a (white) yellow-seeded va- 

 riety. Four peas were obtained, which, though subsequently proven 

 to be true hybrids, did not differ in appearance from the uncrossed 

 seeds borne by the Dwarf Imperial plant. Thus even at that early 



