Roberts: Founders of the Art of Breeding 



151 



of crossing plants artificially, and had 

 even laid the foundations for a knowl- 

 edge of the laws governing hybrids, 

 much doubt still remained in the minds 

 of botanists, regarding the facts which 

 Camerarius' and Koelreuter's experi- 

 ments demonstrated. As Sachs re- 

 marks. "The plant collectors of the 

 Linnaean school, as well as the true sys- 

 tematists at the end of the eighteenth 

 century, had little understanding for 

 such labors as Koelreuter's." 



Gartner says, writing in 1849 (2, p. 5) : 

 "Hybridization in its scientific signifi- 

 cance was so little thought of, and, 

 at the most, regarded merely as a 

 proof of the sexuality of plants, that the 

 many important suggestions and actual 

 data which this diligent and exact 

 observer recorded in various treatises 

 have found but little acceptance in 

 plant physiological papers up to the 

 most recent times. On the other hand, 

 even in respect to the sexuality of plants, 

 they were attacked to such a degree, that 

 their genuineness was doubted and 

 strenuously contradicted, or else they 

 were regarded as a sort of inoculation 

 phenomenon belonging to gardening." 

 Such is the usual history of scientific 

 progress. 



THE REVELATIONS OF SPRENGEL 



While Camerarius had demonstrated 

 the fact that plants possess sex, and 

 Koelreuter had shown that fertile hy- 

 brids could be produced between plants 

 of different kinds, the further fact that 

 crossing in nature, at least among 

 different individuals of the same species, 

 is a common and ordinary phenomenon 

 in the plant kingdom, was not at all 

 known. Aware, as we are today, that 

 the improvement of cultivated plants, 

 due to the appearance of new strains 

 and varieties, is to be accredited largely 

 to the natural crossing of individuals 

 standing in fairly close relationship to 

 one another, we can see the importance 

 to plant breeding, of the next great 

 discovery, that flowers are commonly 

 pollinated by insects, and that there is 

 an intimate inter-relationship between 

 the plant and the insect world. 



Christian Konrad Sprengel (1750- 

 1816), pubHshed in 1793 (8), an epoch- 

 making book, "The Newly Revealed 

 Secret of Nature in the Structure and 

 Fertilization of Flowers," which consti- 

 tutes the third great landmark in plant 

 breeding, after the original discovery of 

 plant sex by the Asiatic date breeders in 

 the unknown past. It was Sprengel 's 

 chief contribution, to discover the fact 

 of insect fertilization. Such a wealth of 

 accurate, first-hand observations on the 

 adaptations of flowers to cross pollina- 

 tions, had never before been made. To 

 Sprengel also is due the discovery of 

 dichogamy, i. e., the maturing of the 

 stamens and pistils of flowers at different 

 times. His conclusion, that nature in 

 most cases, intended that flowers should 

 not be fertilized by their own pollen, 

 and that the peculiarities of flower 

 structure can only be understood, when 

 studied in relation to the insect world. 

 was revolutionary for his time. "Here 

 was the first attempt to explain the 

 origin of organic forms from definite 

 relations to their environment." 



THE SIGNIFICANCE OF SPRENGEl's 

 DISCOVERY TO PLANT BREEDING 



Conceding the fact that plants actu- 

 ally have sex, it is plain that some kind 

 of breeding must be possible. Granting 

 that hybrids, even between different 

 species, can be produced, it is further 

 plain that new kinds of plants can be 

 originated. But what of the additional 

 fact — the contribution of Sprengel — ■ 

 that in general, nearly all flowering 

 plants with deflnite floral envelopes 

 are naturally cross-fertiHzed. It means 

 simply this, that the bringing together 

 of new combinations of parental char- ' 

 acters is the rule rather than the excep- 

 tion in nature, and that, therefore, the 

 breeding of new types in the plant world 

 may be said to be going on all of 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 the diversity — the existence 

 of so many \^ariations in nature, upon 



