438 GENETICS IN RELATION TO AGRICULTURE 



T. porrifolius) which bloomed in 1759, was, according to Focke, the 

 first plant hybrid to be produced for scientific purposes. But Linnaeus' 

 ideas as to the possibility of hybrids between even widely different an- 

 cestors were somewhat fantastic. 



Meanwhile, another investigator had been laboring on many fruitless 

 experiments. Joseph Gottlieb Koelreuter laid the foundation for the 

 modern study of hybridization in plants. It was not until 1760 that he 

 obtained seeds from a cross between two species of tobacco (Nicotiana 

 rustica 9 X N. paniculata cf ). The hybrid plants bloomed in 1761 and 

 the same year appeared his paper on sexuality in plants. He called 

 attention to the role of insects in cross-pollination and estimated the 

 number of pollen grains. According to Focke, but little interest was 

 taken in his work by others as he was decades ahead of his time. He 

 accumulated data of the greatest significance on the characters of inter- 

 specific hybrids. Besides Nicotiana, he worked with several species of 

 Dianthus, Aquilegia, Matthiola, Melandrium, Linum, Malva, Lavatera, 

 Lobelia, Datura, Lycium, Verbascum and Digitalis. 



Toward the close of the 18th and during the first half of the 19th 

 century this work of Koelreuter was extended in some directions by 

 other scientists, notably by Duchesne, Sprengel, Herbert and Gaertner. 

 Duchesne introduced the idea of races into botany and thus helped in 

 breaking down the Linnaean dogma of the constancy of species. Sprengel 

 studied the relations between flowers and insects in great detail. Herbert 

 interested himself in a long series of experiments with species of Erica, 

 Gladiolus, Hippeastrum and Rhododendron, securing many interesting 

 results. He also engaged in a discussion with Knight on fertility in 

 interspecific hybrids. Focke considers this debate in the nature of an 

 introduction to the later more comprehensive controversy between 

 Cuvier and Geoffrey St. Hilaire. Gaertner's experimental work extended 

 over several decades and in number of experiments probably he is sur- 

 passed by no other hybridizer, but unfortunately his records and dis- 

 cussions of results are clumsily reported and, according to Focke, their 

 worth is frequently overestimated. His investigation of fertilization 

 was of greater value. 



During the last half of the 19th century the scientific knowledge 

 of plant hybrids was extended by a number of other investigators whose 

 contributions have been thoroughly reviewed by Focke. Especially 

 significant for agriculture was the work of Godron, Naudin, Nageli, 

 Darwin and Mendel. Godron, by hybridization of wheat and spelt, 

 demonstrated the hybrid origin of Aegilops triticoides and so destroyed 

 the old tradition that spelt had been transformed into wheat. Naudin 

 opposed the conception, still maintained by Cuvier, that species are hard 

 and fast entities and, based on his experiments in hybridizing different 



