ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 989 



from three to seven fleshy white runners, 1-2 mm. in diameter, and in 

 some cases considerably over 2 in. long, with a few scales in the lower 

 part, the rather acute apex somewhat enlarged, and crowded with scales, 

 the inner ones very thick and yellow, forming the young bulb of next 

 year. The runners appear to curve downwards at first, afterwards 

 bending upwards at the apex. 



Torsion of Stems.* — Herr E. Goethe gives particulars with regard 

 ^ to the twisting of the trunk of a number of trees. Many trees, as Popu- 

 lus canadensis and alba, appear never to exhibit torsion, while others, like 

 the horse-chestnut, do so almost invariably. In the same species, or 

 sometimes only in the same variety, the direction of the torsion is 

 always constant ; thus in the horse-chestnut it is always to the right, in 

 the hornbeam to the left. Sometimes it does not manifest itself till the 

 tree is 20 or 30 years old. 



Spines of certain Plants, j — M. A. Lothelier states that numerous 

 botanists have studied the spines of plants ; but they have either exclu- 

 sively noted the external morphology of the organs, or they have studied 

 them from the point of view of their development. The anatomical 

 study has been completely neglected. The author, in this paper, gives 

 the results of some observations on this head. 



If a section be made of the spine of ZTlex europseus, from the middle 

 to the apex, the pith appears thick and already sclerotized ; round the 

 pith are numerous fibrovascular bundles. A sclerenchymatous bundle 

 alternates regularly with each of the fibrovascular bundles, usually 

 corresponding to the number of ribs in the branch. In addition, radial 

 coUenchymatous bands situated opposite the fibrovascular bundles cor- 

 respond to each of the ribs, and assist in sustaining the organ. The 

 spines of Crataegus oxyacantha, as also those of Genista hispanica, 

 Lycium barharum, Citrus triptera, &c., have the mor^ihological value of 

 branches arrested in their development. 



The author concludes with the following remarks: — (1) That in 

 spines there is a reduction of the vessels from the base to the apex, with 

 a gain in the sclerenchymatous elements ; (2) The sustaining elements 

 are furnished by the central cylinder, and especially by the strongly 

 sclerotized pith. (3) All the tissues are differentiated. (4) In spinous 

 branches the growth does not take place at the base, but at the apex. 



Protection of Buds.| — Herr A. Feist has investigated the various 

 arrangements for the protection of the leaf-buds of dicotyledonous trees. 



I. The protection of buds may consist of modified leaf-structures — 

 (a) The great majority of dicotyledonous trees have buds protected by 

 special leaf-like structures of variable morphological nature, but in 

 function exclusively protective. This is the case in Querciis, Fagus, 

 Populus, Ulmiis, Carya alba and tomentosa, Tilia, Maalda, Laburnum, 

 Actinidia, Cephalanthus, AilantJms. (h) Naked buds surrounded by leaves 

 only are exhibited by Pterocarya caucasica, Carya amara, Juglans nigra, 

 Viburnum Lantana, V. Lentago, V. dentatum, Virgilia lutea, liJius 

 glabra, Ptelea mollis and trifoliata, Sophora japonica, Bobinia viscosa. 

 In this case the buds not unfrequently require protection during 

 development, and this is always afforded by various forms of hairs. 



* Gartenflora, xxxviii. (1888). See Bot. Ztg., xlvi. (1S8S) p. 430. 



t Bull. Soc. Bot. France, xxxv. (1888) pp. 313-8. 



1 Nova Acta K. Leop.-Carol. Akad. Katurf., li. (1887) pp. 303-44 (2 pis.). 



1888. 3 X 



