RECENT ADVANCES IN SCIENCE 381 



revision of the Australian Salicornicae is contributed by J. M. 

 Black to the Trans. Roy. Soc. S. Australia. 



In the New Phytologist for July and October, J. R. Matthews 

 discusses the so-called species of Rosa as found in Britain, and 

 shows that the different types observed are mostly explicable 

 on the assumption of the occurrence of numerous segregates 

 of hybrids between a comparatively small number of species. 



Several important papers have appeared during the present 

 year in the Bot. Jahrbilcher. These include contributions to 

 the Flora of Africa dealing with the Families Piperacese (de 

 Candolle), Acanthaceae (Lindau), and Rubiaceae (Krause), and 

 to the Flora of Papua dealing with the Anacardiaceae, Bur- 

 seraceae, Simarubaceae (Lauterbach), Araliaceae (Harms), 

 Sapindaceae (Radlkofer), and Pteridophyta (Branse). Central 

 American species of Piper are the subject of a paper by de Can- 

 dolle in the Bot. Gaz. 



Anatomy and Cytology. — Forsaith has studied the ray struc- 

 ture in alpine and closely related lowland species, and con- 

 cludes that the colder conditions tend towards reduction in the 

 ray storage tissue. 



The anomalous secondary thickening of Chenopodium album 

 has been studied by E, F. Artschwager (Amer. Jour. Bot.), whose 

 conclusions differ in several particulars from those of earlier 

 investigators. The cambium, which is periodically active and 

 forms xylem throughout its extent on the inner side, is " used 

 up " in those parts where, on its outer face, phloem groups 

 are developed. Cambial continuity is, however, maintained by 

 the formation of arcs of meristematic tissue on the outer face 

 of the phloem groups. These latter are chiefly composed of 

 sieve tubes, whilst phloem parenchyma, which has been re- 

 garded as their chief constituent, is relatively unimportant. 



The anatomical structure of abnormal seedlings of Impatiens 

 Roylei is described by Miss Holden {Ann. Bot.), who finds sup- 

 pression of one root pole associated with syncotyly and also 

 disappearance of the first leaf of the epicotyl. 



The anatomy of the stem of Dioon spinulosum is described 

 by Langdon {Bot. Gaz., August), who finds 7-9 strands passing 

 into each leaf, of which 5-7 anastomose to form the two charac- 

 teristic girdle-strands in the leaf-base. Three types of rays 

 are present in the stem. Uphof {New. Phyt., June) describes the 

 anatomy of Xerophytic Selaginellas, and finds that these agree 

 in the proximity of the dorsal and ventral leaves and their 

 similarity in size. The vessels are narrower than in hygrophytic 

 species or plants grown in humid soil. The cells contain a large 

 proportion of oil in contrast to the starch of hygrophytic species. 

 This last observation suggests comparison with xerophytic 

 algae such as Horniidium and Zygnenia. 



