PLANT HYBRIDIZATION BEFORE MENDEL 87 



elusion formulated by Knight, on the basis of his experience, 

 afterwards confirmed by Darwin, and since called the Knight- 

 Darwin law, was that: 



"New varieties of every species of fruit will generally be better- ob- 

 tained by introducing the farina (pollen) of one variety of fruit into the 

 blossom of another, than by propagating from one single kind." (3f, 

 p. 38.) 



However, the work of Knight which attracts the most atten- 

 tion from the standpoint of genetics is his experiment with peas. 

 The paper in question, read before the Horticultural Society, June 

 3, 1823, was entitled "Some Remarks on the Supposed Influences 

 of the Pollen, in Cross-breeding, on the Color of the Seed-coats 

 of Plants and the qualities of Their Fruits." 



This paper is really, in part, a reply to certain phases of the 

 experiments of John Goss upon the same plant. Knight's intro- 

 ductory statement, which follows, is a curious reminder in point 

 of form of Mendel's own introduction to his report upon his ex- 

 periments with peas nearly half a century later. Knight says : 



"The numerous varieties of strictly permanent habits of the pea, its 

 annual life, and the distinct character in form, size and color to many 

 of its varieties, induced me, many years ago, to select it for the purpose 

 of ascertaining, by a long course of experiments, the effects of introduc- 

 ing the pollen of one variety into the prepared blossoms of another. 

 My chief object in these experiments was to obtain such information as 

 would enable me to calculate the probable effects of similar operations 

 upon gther species of plants, and I believe it would not be easy to sug- 

 gest an experiment of cross-breeding upon this plant, of which I have 

 not seen the result, through many successive generations." (sf, p. 378.) 



In the particular experiment in question Knight determined 

 that, in crossing a pea with grey seed-coats upon one with white 

 seed-coats, no immediate change in color took place, but that the 

 resulting hybrid seeds produced plants the next year which uni- 

 formly bore grey seeds, as well as having the purple-colored 

 stems and the flowers of the male parent. He further discovered 

 the fact that by crossing plants grown from these (heterozygous) 

 grey seeds, with pollen from what he calls a "permanent" white 

 variety, plants of two types appeared, one bearing grey and the 

 other white seeds — in other words, in modern terms, the result 

 of the cross of a recessive white upon a hybrid dominant grey. 

 No numbers are reported, so that a scientific basis of ratios, as 

 later found by Mendel, was not laid. 



