PLANT HYBRIDIZATION BEFORE MENDEL 345 



investigational activity. Professor MacLeod, Director of the Botanical 

 Garden in Ghent, discussed quite briefly with me a program of work to 

 carry out pollination experiments with plants to be selected, which 

 should determine, whether perchance, in individual cases, with respect 

 to development of the fruit, differences existed as the result of auto- 

 gamous, geitonogamous and xenogamous fertilization of like or dis- 

 similar species. I had in the beginning the good fortune, quite by chance, 

 to choose for these investigations the Wallflowers, in which xenogamy 

 increased the growth in length of the shoot by about twofold, as com* 

 pared with autogamy and geitonogamy. These experiments were later 

 continued and extended in Vienna.^ since I remained in Ghent only until 

 July, it was a question of looking out for a plant which could bring its 

 vegetation-period to a close by this time. I selected peas, impelled by the 

 reading of Darwin on the effects of cross- and self-fertilization. I was 

 also urged by the incompleteness of the observation-material in the case 

 of this plant with Darwin (only four pairs of plants were measured and 

 compared to complete these experiments). The yield-results from my ex- 

 periments I took with me to Vienna. From these, together with other 

 questions to be answered, since green-cotyledonous peas had been crossed 

 with yellow-cotyledonous, wrinkled-seeded with round-seeded, I had 

 already been able to determine the method of operation of the xenia 

 effect, since the prospective assistant's position was still not yet ooen 

 in 1809, T volunteered for a year on the estate of the Imperial family's 

 foundation in Esslingen, near Vienna, because the setting apart of ^0 

 hectares from this management for the purpose of the founding of an 

 exoerimental establishment for our Hochschule was in prospect. 



'■'There, in the garden of a neighboring estate owner, my experiments 

 with peas, begun in Ghent, were continued, and at the same time, new 

 crosses Instituted with grain and garden beans. The working ud of the 

 F-. of my peas hvbrids, followed in the fall of 1899. In this I was 

 struck especially by the different value of the characters of the indi- 

 vidual races with resnect to their structure, cotyledon-color and form 

 ('see conclusion III of my first paper, in which I emphasized besides 

 th^t. Instead of 'domlnleren' fdomlnatel, one should say rather *ptS- 

 valleren' [predominate], at least In certain cases [see conclusion VIll). 

 In counting out the seed-characters, the ever-recurring number relation- 

 ship of 3:1 could naturally not escape me, any more than the number- 

 relation of 1:1 on back-crossing of green-seeded peas with hybrid pollen 

 of the F, generation. The rules of inheritance, quite Intentionally, I ex- 

 pressed at first purely descriptively or phenomenologically. In order not 

 at once to anchor the newly-beginning experimental phase of the doctrine 

 of heredity — as had happened Inexpediently with Darwinism — to definite 

 theoretical terms. From this standpoint, I designated the regularities 

 found by Mendel and myself, as those of the regularly varying values 

 of the characters for the inheritance, under which I comprehended not 

 only the rule of dominance, but mass-value (domlnance-recessiveness, or 

 equivalence of value) ; quantities-value (the relation of segregation), 

 and Inheritance-value, or splitting per se. 



"Later likewise, I have remained consistently faithful to that stand- 



2 Beihef te der deutschen botanlschen Gesellschaft, 1902, Heft 1. 



