On the Inheritance of Certain Invisible Characters in Peas. 29 



very distinct, and closely resembling the pigmentation which is characteristic 

 of the cultivated variety known as " maple " ; the presence of this character 

 will hereafter be referred to as m. The grey ground colour may further be 

 denoted as g. In the absence of these three characters the testa of a pea 

 is commonly nearly colourless, and this absence of colour in the testa is 

 constantly associated with white flowers and unpigmented axils. The latter 

 group of characters we shall call w. The native pea with which the following 

 experiments were made bears, then, the characters m.p.g. Its flowers were 

 purple and its axils coloured. 



At a recent meeting of the Koyal Horticultural Society, Messrs. Sutton 

 exhibited a cross between a white seeded variety and what was described as 

 a possible wild type of P. sativum, seeds of which had been obtained from a 

 plant found in Palestine by Mr. Arthur Sutton. On examining the seeds of 

 this cross, I found, as I had expected, that they showed both the purple 

 spots and the maple marking on a grey ground colour. 



Of the colour characters referred to, the grey is determined by a greenish 

 insoluble pigment contained in all, or almost all, the cells of the testa. The 

 purple pigment exists in the form of a coloured cell sap, confined to certain 

 large cells of the subepidermal layer. The brown pigment seems to exist 

 chiefly in the cell walls of the outermost layer of I-shaped cells. 



Early in 1903* the Ceylon variety, already described, was crossed with an 

 English pea known as " Sutton's Satisfaction," having colourless testas. The 

 testas of the seeds borne by the resulting plants were all precisely like those 

 of the native parent — m., p., and g. are all dominant. 



In F 2 only 25 plants were raised, which showed the following characters : — 



m.p.g. m.g. p.g. g. w. 



11 2 6 2 4 



In the case of one of the four plants with white flowers, the nearly 

 colourless testas exhibited a very faint brown marbling, like the " ghost " of 

 a maple character. 



These few plants were clearly insufficient to allow of any deduction being 

 made as to the characteristic proportion of F 2 . Three of the above m.p.g. 

 plants, however, yielded once more all the different types in F 3 , being, there- 

 fore, clearly of the same heterozygous constitution as their parents ; 

 169 plants of this description included the following: — 



m.p.g. m.g. p.g. g. w. 



82 20 21 9 37 



And the offspring of the remaining plants showed nothing to contradict the 



