210 PLANT HYBRIDIZATION BEFORE MENDEL 



2. ''The characters of hybrids are derived from the characters of the 

 parents. Only in size and luxuriance, as in sexual power, are they dis- 

 distinguished for the most part from both parents!' (p. 473.) 



With regard to the manner in which the characters are bound 



together in hybrids, Focke makes the following statement : 



"In general a fusion or mutual penetration of the characters takes 

 place, frequently, however, in such manner that in one aspect the one, in 

 another the second parental form appears to prevail. Sometimes, for ex- 

 ample, the hybrid recalls in its leaves more the one, in its flowers more 

 the other parental form." (p. 473.) 



Focke remarks upon the fact that in the crossing of nearly re- 

 lated races, especially color-varieties, plants frequently are de- 

 rived, which resemble exactly or nearly so one of the parent races; 

 citing cases of Brassica rapa^ Linum^ Pisurn, Phaseolus, A/iagalHs, 

 Atropa, and Datura. 



"Only in the second generation," he says, "does the influence of the 

 older parental race ordinarily betray itself, and in this manner that a 

 part of the seedlings completely or in certain respects revert to it." 



(P- 474-) 



"in later generations of the hybrid plants deviations from the char- 

 acters of the parents are still more generally observed." (p. 474.) 



3. "Crosses betzueen different races and species are distinguished, as a 

 rule, through their vegetative activity, from the specimens of a pure 

 race. Hybrids between noticeably different species are frequently very 

 tender, especially in youth, so that the rearing of the seedlings succeeds 

 with difficulty. Hybrids between nearly related species and races are, on 

 the other hand, luxuriant and vigorous; they are distinguished for the 

 most part by size, rapidity of growth, early flowering, abundance of 

 flowers, longer life period, vigorous power of reproduction, unusual size 

 of individual organs, and similar characters." (p. 475.) 



4. "Hybrids of different species form, in their anthers a more limited 

 number of pollen grains, and in their fruits a more limited number of 

 normal seeds than the plants of pure origin. Frequently they produce 

 neither pollen noir seeds. With hybrids of nearly related races this weak- 

 ening of the capacity for sexual reproduction as a rule is not present. 

 The flowers of the infertile or little fertile hybrids remain fresh as a 

 rule for a long time." (pp. 476-7.) 



5. "Abnormalities and structural variations in the flower-parts of hy- 

 brid plants are far more abundant, especially, than on individuals of 

 pure origin." (p. 481.) 



Focke's treatise is often referred to as being noteworthy for 



containing, with the sole exception of Hoffman's memoir (3), the 



only references to Mendel's work anterior to 1900. A. careful 



study of Focke's report brings into interesting relief the reason 



for his having failed to appraise the Mendel paper at its present 



value. In the first place, Focke was especially interested in the 



works of those who produced more extended contributions. The 



