1908.] Theory of Ancestral Contributions in Heredity. 63 



(ii) The Yellows. 



I shall now give a brief account of the various strains of yellow peas used 

 in the experiment. I had been endeavouring for some time previous to 1907 

 to bring together a collection of peas from widely separated sources, with a 

 view to repeating the observations of Mendel and others on a broader basis 

 of material. The yellow strains thus obtained were used in this experiment. 

 I shall briefly describe them in the order in which they occur in my records, 

 writing the catalogue number before the description of them. 



(477) This is a native Chinese cultivated pea, and was procured for me 

 in a village not far from Pekin by Dr. Korsakov, of the Eussian Legation in 

 Pekin. Wen-clou is the name written on the packet in which they were sent. 

 The peas are yellow and round. The pod and the peas themselves are very 

 small, and have evidently not been imported from Europe during the last 

 half century, if, indeed, there is any reason to suppose that they have been 

 imported at all. 



(478) This is one of a set of peas which my colleague, Mr. F. J. Bridgman, 

 procured from a shipping merchant who was kind enough to put up a few 

 packets of seeds from cargoes which had been shipped from various parts of 

 the world. 478 was a particularly fine seed, resembling Victoria marrow, 

 from a cargo which had been shipped from Germany. 



(479) Nineteen seeds of this variety came into my possession at a meeting 

 of the Natural History Society at the Eoyal College of Science during 

 December, 1906. It is a small yellow round pea. 



(480) From Calcutta.^ 



(481) From Canada. l Th ^gh the same channel as 478. All yellow 



(482) FromEussia. J round - 



(492) A yellow round pea which I bought in Genoa in April, 1906. The 

 parents of the plants which were used in this experiment were grown in my 

 garden in 1907. A yellow round pea. 



(493) The same as 492, from a later sowing in 1907. 



Explanation of Tables I— VIII. 

 Cross-pollination was effected in the following way: — A flower of suitable age was 

 selected to function as pistil-parent ; one side of its carina was torn transversely, the 

 whole carina then temporarily slipped off the bunch of stamens, which were removed with 

 forceps, after it had been determined that they had not yet dehisced. A flower of suitable 

 age to function as pollen-parent was selected and plucked from the plant which bore it ; 

 the tip of its carina was cut off and the stigma of the pistil-parent was inserted into the 

 aperture in the carina made by the cut, and consequently into the mass of pollen which it 

 contained. The carina of the pistil-parent was then slipped back, and the standard and 



