Varietäten, Descendenz, Hybriden. 185 



3) crosses between large- and small-flowered species, which some- 

 times yield pure breeding patroclinous hybrids, someiimes twin h}''- 

 brids; 4) Mendelian behaviour in certain characters. 



It is held that O. Lamarckiana, as an open-pollinated plant, is 

 naturall}' not a pure type; and that many of the mutational pheno- 

 mena are an expression of germinal instability resulting from cross- 

 ing of races in the ancestry. 



An analytical key to the species of the § Onagra is given, the 

 primary divisions being on 1) the size of the petals, whether 12 — 30 

 mm. or 30—60 mm. long; 2) the relative length of style and stamens. 

 Cultures of Oenotheras from various localities where \hey are native 

 or allen show immense polymorphism, and every evidence of a,great 

 amount of crossing. The offspring of 0. niuricata usually consists of 

 a mixture of broad-leaved and narrow-leaved plants. A preliminary 

 account is given of the races derived from the extensive and com- 

 plex colonies on the Lancashire (England) coast. 



The Problems of evolution and adaptation are discussed in the 

 light of recent work on mutation, and it is concluded that simple 

 factors such as natural selection and mutation are inadequate to 

 account for all evolution, though both these factors have plaj'ed 

 their part. R. H. Compton (Cambridge). 



Thomas, R. H., Nicotiana Crosses. (Rapports IVieme Conf. int- 

 Genet. p. 450—460. Paris 1913.) 



Nicotiana Sanderae X -^'- <^ffi^tis fournit en F^ des plantes ä 

 fleurs rouges et des plantes ä fleurs violettes avec disjonctions en 

 rouges, violets et blancs, ou en violet et blancs, en Fo. N. sylves- 

 tris X ^^- affinis produit, en F^ des plantes ä fleurs rouges, des 

 plantes ä fleurs violettes et des plantes ä fleurs blanches. N. San- 

 derae X ^ • sylvestris fournit un type assez uniforme , sauf dans la 

 couleur de la coroUe oü il apparalt trois tons differents de rose. 



La forme du pollen: gros ovale {N. sicaveoletis), carre et ovale 

 ä bouts carrös {N. Tabacum), rond (TV. sylvestris), est hereditaire 

 et la segregation en a ete observee dans plusieurs croisements. 



L. Blarinofhem. 



'es' 



Thomas, R. H., Note sur la Parthenogenese chez les plan- 

 tes. (Rapp. IVieme Conf. int. Genet. p. 209. Paris, 1913.) 



Un Tabac de Cuba {Nicotiana sp.?) fournit un assez grand 

 nombre de fruits parthenogenetiques; Oenothera hiennis a donne 

 aussi des graines fertiles sans fecondation prealable. 



L. ßlaringhem. 



Trabut, L., Observations sur l'origine des Avoines cul- 

 tivees. (Rapp. IVieme Conf. int. Genet. p. 336-346. 10 fig. Paris 

 1913.) 



II existe, d'un part, des liens unissant Avena sterilis la mieux 

 caracterisee ä l'Avoine cultivee en Algerie {A. sterilis algerieusis 

 Trabut, avec reduction de l'arete et consolidation de l'articulation), 

 d'autre part des series de caracteres morphologiques et physiologi- 

 ques qui ne laissent aucun doute sur les affinites de ces 'especes. 

 Beaucoup de t3'pes d'Av. sativa fönt des retours ä A. fatua\ A. bre- 

 vis se rattache ä A. strigosa et derive par consequent d'un A. 

 barbata\ A. Wiestii Steudel se relie de meme ä A. abyssinica. 



