Varietäten, Descendenz, Hybriden. — Physiologie. 325 



Henry, A., On Elm-seedlings showing Mendelian Results. 

 (Journ. Linn. Soc. XXXIX, p. 290—300. 2 pl. 1910.) 



Of the numerous elms found in Britain, two — Ulmtis montana 

 and U. glabra — are regarded by the author as true species. The 

 other varieties (with perhaps the exception of IJ. campestris, whose 

 possible relation to the Italian Elm is still the subjectof investigation) 

 are looked upon as derivative forms, resulting from the intercrossing 

 of the two species with one another and with hybrids. 



The Huntingdon Elm {U. vegeta) is considered to be the first 

 cross between U. glabra and U. montana. 



Experimental evidence in support of these views has been ob- 

 tained from sowings of seed set under natural conditions. The 

 author finds that only two elms, namely U. montana and U. glabra, 

 give uniform seedlings. All the other kinds have given mixed off- 

 spring, of different sizes, different arrangement of the leaves, etc. 

 Seed to the Huntingdon Elm was obtained from one of several trees, 

 growing together and not mixed with elms of other kinds. "There 

 was no possibility here of contamination with the pollen of other 

 kinds" of elm. The crop of seedlings thus obtained consisted of 

 plants with opposite leaves and plants with alternate leaves, in 

 numbers closely approximating to the ratio 3: 1. Further examina- 

 tion suggested that four kinds of offspring occurred, namely (1) 

 Small, opposite-leaved; (2) Large, opposite leaved; (3) Small, alternate- 

 Icaved ; (4) Large, alternate-leaved ; the four types being perhaps in 

 the proportions of 9: 3: 3: 1. The plants further differed as regards 

 the length of the petiole. The author concludes that the possible 

 combinations of these characters would allow of nearly all the 

 known varieties of Elm appearing in the F^ generation obtained 

 from the seifing of the Huntingdon Elm. 



"These experiments seem to show that what are called varieties 

 are often simply Mendelian combinations of two existing species." 

 In the light of these results the author briefly reviews the problems 

 presented by some of the varieties of Popuhis, Salix and Qtiercus, 

 and calls attention to the hybrid origin of the "Luccombe Oak" and 

 the diversity of form shown by the seedlings obtained from it. The 

 characters of certain Elms and of the Luccombe Oak, its parents 

 and offspring are illustrated from photograps. R. P. Gregory. 



Doby, G. von Ueber die Oxyd äsen. (Mag. bot. Lapok. IX 

 10/12. p. 407—408. 1910.) 



Nach Besprechung der Hypothesen von Chodat und Bach 

 über die Zusammensetzung der Oxydasen erläutert Vortragender 

 an Hand der Arbeiten von Palladin die Bedeutung der Phenolasen 

 und Tyrosinasen. Sie sind es ja, die in Gemeinschaft mit anderen 

 Enzymen und durch Vermittlung gewisser Chromogene die physiolo- 

 gischen Oxydationsvorgänge in den Pflanzen bewirken u. zw. unter 

 der Leitung des Plasmas. Die Oxydasen spielen aber auch eine 

 schützende Rolle in den Harzen und Milchsäften. Dass sie durch 

 übermässige Wirkung auch Pflanzenkrankheiten verursachen, konnte 

 der Vortragende nicht bestätigen. Mit Ausnahme der Purinoxydasen 

 spielen die Oxydasen bei den Vorgängen der Entwicklungserregung 

 sowie als Schutzmittel gegen Krankheiten eine grosse Rolle. 



Matouschek (Wien). 



Karzel, R. und L. von Portheim, Beobachtungen über 



