138 THE PLAXT WORLD. 



NATURAL HYBRIDS. 



At the international conference (^n Genetics, held nnder the 

 anspices of the Royal Horticnltnral Society of London, in 

 Angnst, 1906, ]\Jr. E. G. Camns presented the resnlts of a study 

 of over thirty years upon the spontaneous hybrids of Europe. 

 The complete paper contains the hil)liography. synonyms, geo- 

 graphical distribution and herbarinni notes, and was much too 

 large to be published in full. Tn the brief abstract which was 

 read before the Society, Mr. Camus finds onlv two classes of 

 hybrids; those which are goneoclinic to the i)istil parent and the 

 other to the pollen parent, and since he has dealt chiefly with 

 herbarium material, has not gone into the segregation of char- 

 actors in the second generation. The whole paper is in fact a 

 study of hybrids from the point of view of the systematist rather 

 than of the experimentalist. ]\Ir. Camus believes that hybrid- 

 ization is least common in species in which pollination occurs 

 early in the development of the flower. Among (»ther favorable 

 circumstances, dioecism is one of the conditioas wliich ])vom()to 

 it. This })aper of course, represents a detailed study of the flora 

 and indicates that the hybrid constituents form a very large ])ro- 

 portion of it. When a similarly minute examination is made of 

 American plants, a corresponding accretion to the list of hyhi-ids 

 may be expected. 



While this author does not })resent any analysis of successive 

 generations of hvbrids, vet he notices that several intermediate 

 forms result when two willows are hybridized. 



At the same conference. Professor MacEarlane of the Uni- 

 versity of Pennsylvania, presented a paper dealing with the nat- 

 ural hyl>rids of the sarracenias in which he demonstrates that N. 

 [jarpHn'd . S. fluni. ^'. inhuir. S. psiffacina and S. dnuiuitoiidn 

 hybridize in the wild state when groAving in close proximity. 



]\fr. R. Irwin Pynch, Curator of the Botanic Garden at 

 Cambridge, presented a discussion of certain British and Conti- 

 nental hvbrids which o-oes far to sustain the contention of Kerner 

 as to tlie im])ortance of such forms in the wild flora. 



