PLANT HYBRIDIZATION BEFORE MENDEL 353 



"In respect to color, Telephone No, 2, with cotyledons yellowish or 

 whitish-green, sometimes also completely clear yellow, X Pois d'Auvergne 

 No. 9, with cotyledons pure yellow ; the F, hybrid seeds were found to 

 be in general yellow, but with plainly visible green spots, [ib., p. 507.] 

 In like manner, the crossing of Couturier No. 6, with orange-yellow 

 cotyledons, with Express No. 14, with light green cotyledons, instead of 

 giving pure yellow, gave a transition tone between yellow and green. 

 Pois d'Auvergne, No. 9, cotyledons dodder-yellow-orange, with Telephone 

 No. 2, yellowish or whitish-green, gave instead of pure yellow, a green 

 spotting on the otherwise yellow cotyledons." (ib., p. 507.) 



"Likewise in respect to form, cases are not lacking in which the ordi- 

 narily dominating compared with the ordinarily recessive in a certain 

 relationship." (ib., p. 508.) 



The cases, however, do not appear to have been quite so clearly 

 defined as the preceding. 



After an extended further discussion of the relation of the 

 pollen to the character of the pod in the seed parent, von Tscher- 

 mak remarks as follows, citing the older literature of Darwin, 

 Gartner, Knight and Laxton : 



"My experiments have most points of resemblance to the observations 

 of Gregor Mendel, who worked with 34 varieties of peas. Fro7n his is 

 derived the above adopted and strengthened conception of dominating 

 and recessive characters. In seeds obtained through artificial pollination, 

 he observed the former (yellow) coloration, and roundness. His results 

 with respect to the crossed plants, studied through several generations, 

 will have to be entered into later. 



"It must be cited, as the especial service of this observer, that he recog-- 

 nized the regularly unlike value of the different characters for inheri- 

 tance, and demonstrated it clearly, for the especially adopted species, 

 Pisum sativum." (pp. 513-14.) 



This is the first extended reference to Mendel in this paper. 

 One of von Tschermak's observations referred to a phenomenon 

 under the name used by Gartner, of Pravalenz (prepotency). 



Twelve crosses, with reciprocal crosses, constituted the experi- 

 ment. Quoting: 



"In the last four cases, of form, and in part color-difference of the 

 parent sorts, and of indicated commingling of characters in the product, 

 each of the parent sorts showed (relatively) more influence upon the 

 constitution of the crossed product, whe^ it furnished the seed-pod, than 

 when it furnished the pollen." (ib., p. 514.) 



The last thirty-four pages of the memoir, constituting Part IV 



of the von Tschermak paper, are devoted to the subject, "Beo- 



bachtungen an den durch kiinstliche Kreuzung erzeugten Misch- 



Hngen." (Observations on hybrids produced through artificial 



crossing.) 



