Descendenz und Hybriden. — Physiologie. 3b5 



wholly identic with the parent plant. That goes to show that 

 constant races may develop little by little from inconstant forms 

 originated by Hybridisation. It seems therefore highiy pro- 

 bable that a pröduction of species is going on also through 

 Hybridisation, as suggested by Pocke. 



Besides tHe true, more or less intermediate, Hybrids also 

 false Hybrids, as already pointed out by Millardet, origi- 

 nate from Hybridisation; tHe'y are wHolly identic with the mother 

 plants. Among the Riibi the disposition to produce 

 false Hybrids is mucH greater than to produce 

 true ones. It is to be noted, that castration of the flowers 

 always Has given a negative result, and that consequently 

 no parthenogenesis (in vvide sense) occurs in the 

 gen US. Perhaps the pröduction of false hybrids may be ex- 

 plained, as also suggested by Pocke, in that way, that the 

 pollen of the foreign father gives only the Stimulus to deve- 

 lopment. 



THe so called Riibi corylifoUi consist of 1. wHolly constant 

 species, 2. inconstant forms, which, without being primary 

 Hybrids, produce a polymorph offspring. The inconstancy is 

 probably based on a Hybridisation in earlier generations. 



Through fertilisatibn of black-fruited Riibi with Riibiis 

 caesiiis Hybrids originate, which morpHologically exactily agree 

 with some Riibi corylifoiU, but which are inconstant. It seems 

 highly probable that a good deal of our native (SwedisHj Riibi 

 coryllfolll have originated in this way; but it sHould be preci- 

 pitate to suppose such an origin to all Riibi corylifoUi. 



C. H. Ostenfeld. 



Cadevall Y Diars, 0. J., La circumnutation enel genero 

 Medicago. Notas fitographicas. (Mem. de la R. Acad. 

 de e. y artro de Barcelona. 1905. Vol V. No. 12.) 



En etudiant les especes de Medicago recoltees en Catalogue 

 l'auteur reconnait que le sens dextrogyre ou levogyre de la 

 courbature des fruits de ces plantes n'a aucun valeur pour la 

 determination des especes. II pourra etre utile seulement pour 

 les Varietes. II termine cette note par l'enumeration de 20 especes 

 de Medicago recoltees en Catalogue. 



Dans les Notas fitographicas, l'auteur fait la des- 

 cription de quelques especes nouvelles qu'il a recoltees: 

 Jiuiipenis Mariana (]. phoenicea X communis), Fumaria cal- 

 carata dont le facies est celui du F. officinalis et le fruit du 



F. micrantha ; F. parviflora Lamk. subsp. microsepala. 



J. Henriques. 



DE Gasparis, A., Considerazioni intorno al tessuto 

 assimilatore di alcune specie del genere Portulaca. 

 (Atti della R. Accad. delle scienze fis. e matem. di Napoli. 

 Vol. XII. Ser. 2. No. 11. Napoli 1905.) 



En se reportant ä un ouvrage precedent public en 1900, 



relatif ä l'individualisation des cHloroplastides de Pellionia 



