Biologie. — Morphologie und Teratologie. 275 



physiologique pensent que l'apparition des colorations florales 

 n'a point ete provoquee par l'intervention des insectes, mais 

 au contraire par des conditions interieures de la fleur eile 

 meine. Dans celle-ci l'accumulation des produits d'assimilation 

 doit avoir cause d'un cöte l'inutilite d'abord, suivie apres de la 

 metamorphose des chloroplastes, de l'autre cöte le debut des 

 colorations anthocyaniques; une iois que celles-ci ont pris 

 origine elles ont ete fixees et etablies par l'intervention des 

 insectes qui par consequent ne peuvent etre consideres comme 

 les excitateurs de cette grande metamorphose. 



10° Aussi le probleme etabli par les auteurs sur la phylo- 

 genie des anthocyanines a ete resolu en admettant que l'evo- 

 lution chromatique des fleurs n'est point monophyletique mais 

 polyphyletique, la derivation de l'anthocyanine des pigments de 

 la serie xanthique ou vice versa la formation de ceux-ci des 

 couleurs anthocyaniques etant inadmissible. 



Cavara (Catania). 



Mac Dougal, D. T., Some Aspects of DesertVegetation. 



(Plant World. Vol. VI. p. 249—257. PI. 33—36. fig. 1 



— 5 in text.) 



Mentions seven groups oi plant forms characteristic oi the desert 

 regions ofSouthwestern North America, with the reservation that 

 such a Classification is not intended as an exhaustive analysis of the 

 types of Vegetation. I. Herbaceous annuals, which develop quickly from 

 the seed during the growing season. The vegetative parts of the plant 

 are not xerophytically modified; it is the seed that resists the dry season. 

 II. Perennials which have woody, bulbous or tuberous stems, which lie 

 dormant during unfavorable season and produce a rosette of leaves and 

 a shoot during the rainy period. III. Perennial shrubs or trees which 

 bear deciduous leaves during the rainy season, some of which retain 

 their leaf petioles for long periods after the leaves themselves have 

 fallen. IV. Perennials of a spinescent habit with reduced leaf suriace 

 and which do not exhibit any very marked seasonal alterations. V. Per- 

 ennials with leaves that are protected by waterproofing material or are 

 furnished with volatile oils. VI. Perennials of the succulent type and a 

 reduced transpiratory area, the cactus type. In Cactus greggii the 

 main root and base of shoot are greatly swollen and the rest of the shoot 

 is reduced to an extreme. VII. Species adapted to soils containing large 

 proportions of soluble salts. In conclusion suggests that the explanation 

 of many of the special features of desert Vegetation are the result of an 

 optimistic interpretation, rather than being based on actual Observation. 



H. M. Richards (New-York). 



LOPRIORE, G. et CONFGLIO, G., Lafasciazione delle radici 

 in rapporto ad azioni traumatiche. (Atti dell' Accad. 

 Gioenia di Sc. Natur. Catania. Vol. XVII. 1903 p. 1—56.) 



Si la fasciation des tiges ä ete depuis longtemps l'objet de 

 recherches, il n'en est pas de meme pour celle des racines sur 

 laquelle ou a jusqu'ä present tres peu d'observations. Les 

 auteurs ont remarque qu'on peut provoquer cette deviation du 

 de'velopement normal sur les racines de Feve et de Mais cultivees 

 dans des Solutions aqueuses, et en agissant sur elles avec des 



18* 



