82 PLANT HYBRIDIZATION BEFORE MENDEL 



Conceding the fact that plants actually have sex, it is plain 

 that some kind of breeding must be possible. Granting that hy- 

 brids even between different species can be produced, it is fur- 

 ther plain that new kinds of plants can be originated. But what 

 of the additional fact, the contribution of Sprengel, that in gen- 

 eral nearly all flowering plants with definite floral envelopes are 

 naturally cross-fertilized. It signified that the bringing together 

 of combinations of parental characters is the rule rather than the 

 exception in nature, and that, therefore, the breeding of new types 

 in the plant world may be said to be going on all the time. It 

 remained for Darwin to show how the results from such perpetual 

 crossings are limited and held in check by the operation of natural 

 selection. At all events, Sprengel's discoveries at once disclosed at 

 least an important reason for diversity, for so many variations in 

 nature, upon which fact man had unconsciously depended for the 

 selection of "superior" types of plants, and hence for the "im- 

 provement" of races. 



Unfortunately, the discoveries and disclosures of Sprengel 

 awakened little interest at the time. Like the work of Camerarius 

 and Kolreuter, the investigations of Sprengel, in turn, suffered 

 comparative obscurity. Biologists of his day believed in the dogma 

 of the fixity of species, upon which Kolreuter's and Sprengel's 

 experiments and discoveries regarding cross-pollination by means 

 of insects tended to cast doubt, and to require the substitution, 

 for the doctrine of the fixity of species, of the principle of the 

 comparative stability of organic forms. 



Although the scientific world traces a continuity of thought 

 and investigation from Gartner back to Camerarius, the fact must 

 not be lost sight of that each of the three chief investigators who 

 laid the early foundations of plant genetics, Camerarius, Kolreu- 

 ter, and Sprengel, was considerably ignored by the biological sci- 

 ence of his own time. 



Two generations elapsed from the time of Camerarius to that 

 of Kolreuter, and another from Kolreuter's time to that of Spren- 

 gel. It is more than a fourth generation from Sprengel's publica- 

 tion to the time of the work of William Herbert (1837) ; a third 

 of a generation more to the appearance of Gartner's memoir 

 (1849), and about half of another generation again, before the 

 appearance of Mendel's celebrated papers (186:6^, and finally, 



