154 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



and artificially cooled as they approached the tropics, by which means 

 a constant supply of flowers was produced during the two months' 

 voyage. One result of the experiment was the surprise and pleasure 

 shown by the native inhabitants of Buenos Ayres, who were enabled 

 to enjoy their first sight of lilies of the valley and lilacs. — M. L. H. 



Hooklike Organs, Structure of. By Reinhard Wegener 

 (Beih. Bot. Cent. xxxi. Abt. i, Heft i, pp. 43-89; 26 figs.). — The 

 author describes the anatomical structure and function of the hairs 



of Asperula, Rubia, Hop, Galium, Parieiaria, and Panicum veyticillatunii 

 also of the trichomes of Thladiantha, Apios, Desmodium, o-nd Aristolochia, 

 and of the emergencies and phyllomes of Arctium, Xanthium,Agrimonia, 

 Sanicle, Geum stigmas, Medicago spp., Acaena, Bidens, and Echino- 

 spermum. 



The paper should be of great interest to biologists, and the figures 

 bring out clearly a number of minute points in shape, &c., which are 

 clearly adaptive. Amongst others may be mentioned the very general 

 cutinization of the cell-wall of trichome hooks, the socket-hke base 

 of the hooked hairs of Rttbia, the peculiar way in which the upper 

 branch of the Hop trichome acts as a buttress and yet does not inter- 

 fere with upward growth, the extraordinary development of cutinized 

 supports at the base of hairs of Apios tuber osa, and the separation 

 layer and minor adaptations in Geum styles. 



The longitudinal sections of the spine of Acaena ovalifolia and 

 Echinospermum Lappula are particularly beautiful examples of 

 mechanical engineering in plant tissues. — G. F. S, E. 



Hydro charidaceae, Leaf-Anatomy of. By H. Solereder, Er- 

 langen {Beih. Bot. Cent. xxx. Abt. i. Heft i, pp. 24-104 ; 53 figs.). — 

 There are three marked types of leaf in this order : [a] One-nerved, 

 sessile, and submerged, as in Elodea ; (b) long, grasslike, with longi- 

 tudinal and transverse nerves, as in Vallisneria ; (c) the type of Hydro- 

 charis with blade, leaf- stalk, and several nerves. Palisade tissue and 

 stomata are only found in the air leaves, as e.g. of Stratiotes. Secretory 

 cells are common and are only wanting in four genera. 



There are no special anatomical characteristics of this family 

 considered as a whole. Raphid-bundles do not occur, though raphides 

 are found. 



The genera described are the following : Halophila, Hydrilla, 

 Elodea, Lagarosiphon, Vallisneria, Blyxa, Enalus, Thalassia, Stratiotes, 

 Otielia, Bootiia, Hydrocharis, Limnobium, and Hydromystria. 



G. F. S. E. 



Hypericum calycinum (grandiflorum) {Rev. Hort., pp. 314-15, 

 Nov. 16, 1913). — Highly recommended for the formation of protective 

 belts of vegetation between forest areas, as, owing to its dense and 

 low growth and non-inflammable character, it is admirably adapted to 

 prevent the spread of fires. It is quite hardy, immune from destruc- 

 tion by game, grows vigorously under dry conditions and either in 

 sun or shade, but is rather too assertive for garden culture. — C. T. D. 



