96 



PKOCEEDIXGS OF THE 



manner. Some fifteen years ago, in 'JNature,' I ventured to 

 express a similar idea based on studies of orchid hybrids. Since 

 then the results of Mendelian experiments, as Dr. Lotsy has 

 shown, have contributed largely to the facts on which the theory 

 is based, and it may interest Dr. Lotsy to know that unpublished 

 data of my Berheris hybrids provide another illustration of the 

 possibilities of the " origin of species by crossing " perhaps even 

 more striking tlian the remarkable series of Antirrhinum hybrids 

 that he has exhibited here to-night. 



At the same time I cannot but feel that the new facts have 

 added some difficulties to our acceptance of the theory as a final 

 solution of the problem of species. One difficulty is that, while 

 crossing undoubtedly causes variation in the second generation, 

 yet in all plants that are naturally cross-fertilized the new forms 

 that arise must be for the most part permanently heterozygous 

 and consequently unstable. 



Another important question seems to arise out of our experi- 

 ments. Is it certain that the morphological characters which 

 characterize systematic species are of paramount survival value? 

 Is it not possible that certain physiological characters, though less 

 obvious, may be more important? May not such qualities as 

 vigour of constitution and high productiveness be the critical 

 characters which really determine the survival and distribution 

 of organisms, whatever their morphological characters may be? 



If so, the questiou of the " origin of species " fundamentally 

 would appear to be a physiological rather than a morphological 

 problem. 



Experiments with cultivated plants and domesticated animals 

 show that, except in some extreme cases, crossing certainly ])ro- 

 motes vigour of constitution and productiveness. It maj'' well be 

 that in this respect, as in others, crossing is a most important 

 factor in the evolution of species. 



Mr. Aethuk Sutton exlnbited a lantern-slide showing a reprn- 

 duction of Gerard's Wild Beet {Beta maritima), wliich is generally 

 accepted as the source from which the 



(a) Mangel Wnrzel, 



{b) Garden Beet, 



(c) Sugar Beef, 



(d) S[)inach Beet, 



(e) Sea-Kale Beet, or Swiss Chard, 



have all been derived. 



All of these perfectly distinct plants have been developed as 

 sources of foorl supply either by root devehijjment, as in the case of 

 Garden Beet, Sugar Beet, and Mangel Wurzel, or by development 

 of foliage, as in the case of Spinach Beet and Sea-Kale Beet, and 



