THE GENESIS OF NEW SPECIES. SYV 



species known as Salix incana and Salix daphnoides respectively, and it was 

 apparently intermediate in form between those two species. The hairs, the system 

 of ramification, the foliage, and the flowers resembled those of S. incana in some 

 respects and those of S. daphnoides in others, and a single glance would have 

 led any unbiassed observer to conjecture that he had to deal with the product of 

 a cross between these two species. 



This discovery,^ made in one of the first years of my career as a student of 

 Botany, chanced upon a time when Botanists were beginning to take a particularly 

 keen interest in all cases of intermediate forms observed growing in a state of 

 nature. Some of the leading men at that time refused to believe in the existence 

 of any wild hybrids, and were of opinion that the supposed cases were varieties of 

 species whose presence was to be explained by a tendency in the plant itself to 

 change its form. They also held the view that all plants between which one or more 

 intermediate forms had been found to exist were to be included in a single species, 

 and, in accordance with this, they not infrequently treated three, four, or more kinds 

 of plant previously classed as distinct species as being really "varieties" of a single 

 species, because forms obviously intermediate between them, i.e. so-called "transitional 

 forms", had been discovered. This practice was carried so far that several systematic 

 Botanists of that day included in one species 5, 10, and even 15 distinct Hawk- 

 weeds which had been previously described as separate species, the reason for the 

 change being that they were all linked together by transitional forms. Another 

 school of Botanists, on the other hand, recognized in most of the so-called transi- 

 tional forms the results of natural crossing, but they did not deny the existence in 

 plants of a capacity to form varieties in the Linnean sense in response to changes 

 of soil or climate. 



To my mind even at that time there could be no doubt which of the two oppos- 

 ing theories concerning the genesis, significance, and position of intermediate forms 

 was to be preferred. The discovery of the hybrid Willow referred to led to my 

 paying particular attention to plant-hybrids, and in the course of the last forty 

 years I have made extensive series of experiments to clear up many obscure points, 

 and to correct the prejudices which then prevailed. 



One misconception as to the nature and significance of hybrids, which had great 

 weight and found expression in the name of " bastard " assigned to them, consisted 

 in the idea that they were contrary to nature. The German word "bastart" is defined 

 by Grimm as a base and useless species. This prejudice was carried so far that 

 Kant positively denied their independent existence, and believed they must neces- 

 sarily die out with the first generation. Connected with this notion was another, 

 according to which hybrids were destitute of the power of producing fertile seeds 

 and propagating their kind sexually. It probably arose from observation of the 

 hybrids of the Mullein genus ( Verhascum), which in Central Europe are so common 



^The little paper recording the finding of this Willow, with some additional remarks, by Anton Kerner, was 

 published in 1852 (Vienna, Zool. Bot. Ver. Verhandl. XL, 1852). This seems to have been Kerner's second 

 definite contribution to science; what would appear to be his first is printed in the sarae publication a few 

 months previously. 



Vol. II. 87 



