PLANT HYBRIDIZATION BEFORE MENDEL 351 



of the incompleteness of the observation-material in Darwin's case, cal- 

 culated upon a larger scale (on the basis of an exact numerical test) 

 were intended for the investigation of this exceptional case. As I became 

 acquainted with the further literature in question upon experiments car- 

 ried out with peas, I introduced in addition a series of other experi- 

 ments, which deal with the inheritance of the characters of unequal 

 value, dominant or recessive (Mendel), and which should especially 

 determine exactly the results of the immediate influence of foreign 

 pollen upon the structure of the fruit produced thereby, or the simul- 

 taneous operation of two pollen species in many-seeded fruits. The ex- 

 periments were begun in the year 1898, in the Botanical Garden in Ghent, 

 the Director of which. Professor MacLeod, has bound me in gratitude 

 through the active interest which he manifested toward my researches." 



The writer proceeds to comment on the fact that, in recent 

 times, methods for the artificial crossing of grain varieties had 

 been published in large measure, but for peas in lesser detail. 



"Concerning the process of the artificial crossing of peas there exist 

 only scanty statements." (3b, p. 468.) 



Mendel's work is thus alluded to {ib.^ p. 468) : 



"Crossing experiments with peas for purely scientific purposes, have 

 been carried out by Gartner £'Bastardierung im Pflanzenreiche,' 1849, 

 pp. 7iff.) ; Darwin ('Variation,' Chaps. 9, 11; 'Cross- and Self-fertiliza- 

 tion,' p. 151) ; and Gr. Mendel ('Verhandlung der Naturforscher Verein,' 

 Briinn, 1865, IV Bd., pp. 3 ff.)." 



The experiments of von Tschermak in 1898 comprised ten 

 pots for each variety used, each with 4-5 seeds, the two most vig- 

 orous being left to grow to maturity. In this experiment, the re- 

 sults of close and self-fertilization were also considered. 



"The experiments pursued primarily the same end, of obtaining ma-, 

 terials for evidence regarding self-fertilization and crossing, in order to 

 be able to repeat in the following year, the test experiments of Darwin." 

 (3b, p. 476.) 



"The continuation of the experiment was carried out in the spring of 

 1899, in a walled garden in Esslingen [Lower Austria]." {ib., p. 477.) 



Since this portion of the experiment does not touch the Men- 

 delian question, it need be no further noticed. 



Later in the course of the same experiment, the following state- 

 ment occurs: 



"My experiments showed first, that frequently, and indeed under dif- 

 ferent conditions, even in the constitution of the seeds the influence of 

 the pollen originating from the other variety could be recognized." {ib., 

 p. 505.) 



Commenting further, it is stated : 



