52 PLANT HYBRIDIZATION BEFORE MENDEL 



with the same regularity and uniformity, as in natural plants and the 

 first hybrid originally produced therefrom'' (p. 144.) (Italics inserted.) 



This sentence is quoted in order to give as clear a picture as 

 possible of the attitude of a scientific mind of that time upon the 

 subject of the so-called "increase in variability" in hybrid genera- 

 tions after the first. 



Kolreuter found that although the Chinese pink and the Car- 

 thusian could be successfully crossed, it was extremely difficult 

 to cross the Chinese with the garden pink. 



"One will, among a hundred flowers, often scarcely find ten, which 

 are actually fertilized, and which contain one, or at most two to three 

 perfect seeds." (p. 150.) 



An interesting genetic fact was ascertained in a cross between 

 Dianthus chinensis X ^« hortensis, in which the latter had 

 "double" flowers, and in Dianthus chinensis ft, simpl. X D. chi- 

 nensis ft. quadrupL, the result being the dominance of the mul- 

 tiple-petalled corolla in the F^. The statement is briefly made re- 

 garding the former cross (p. 152), with respect to the hybrid: 



"its flowers were all reduplicate, and consisted commonly of 15-20 

 quite carmine-red leaves ; from which one plainly sees, that the pollen 

 of doubled flowers possesses the character of reduplicating simple ones 

 >vhich are pollinated with it." 



This statement is extremely interesting because of the germ of 

 genetic thought which it manifests in the mind of Kolreuter. From 

 the second cross above mentioned, he obtained nine plants, among 

 which the most bore quadrupled — i.e., twenty-petalled flowers, 

 (p. 157.) Kolreuter remarks, "this experiment thus confirms that 

 one which has already been noticed above, p. 28, XL Expt." 



The thing that immediately suggests itself to Kolreuter's mind 

 through these experiments is the opportunity offered for improv- 

 ing poor single flowers by crossing with doubles. 



In the case of a wild plant growing in the neighborhood of 

 Calw, Dianthus plumarius^ Kolreuter remarks upon an extraor- 

 dinary condition found by him in the pollen of occasional plants 

 of the species, in which the pollen was of a dark-brown to purple- 

 red color, the grains being much smaller than natural. On polli- 

 nating a Chinese pink with this pollen he obtained no seeds, the 

 flower remaining open for ten days. But on pollinating with the 

 ordinary whitish-grey pollen, the plants closed in twenty-four 



