ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 271 



All the sections of Pinus, with tlie exception of Abies, have two kinds 

 of cells in their medullary rays, the normal, and those called " trans- 

 verse tracheids," which always possessed bordered pits and frequently 

 spiral thickenings. 



The particulars of these various structures are described in detail 

 with respect to a large number of species of Conifers. 



The author finds chromic acid an exceedingly good substance for 

 removing the resin from the resin passages and cells of the medullary 

 rays and parenchyma of the wood. 



Leaf-stalk and Cushion.* — According to Herr P. Prenss, the 

 most widely distributed element in these organs is the collenchyma ; 

 then follows the bast; the libriform plays a subordinate part; the 

 formation of the scattered sclerenchymatous cells is not clear. The 

 most abundant kinds of vessels are the reticulated and the pitted. 



Herr Preuss classifies leaf-stalks and cushions under three types, 

 which are not, however, sharply distinguished from one another, 

 viz. — 



1. Leaf-stalk nearly of the same thickness throughout, not dis- 

 tinguishable into a cushion and a thinner part, (a) without bast and 

 libriform, (b) with bast or libriform. 



2. Leaf-stalk with a cushion at both upper and lower ends, and 

 with the intermediate portion not flexible. 



3. Leaf-stalk with a cushion at each end, and with the intermediate 

 portion moderately flexible. 



Structure of the Bundle-sheath.f — M. C. van Wisselingh describes 

 the structure and development of the sheath which surrounds the 

 central cylinder in the root of Phanerogams. In the species examined 

 it is derived from the outermost layer of the plerome. The outer 

 and inner walls of the cells composing it are marked by stronger 

 thickening, while on the radial walls neither a middle lamella nor a 

 primary thickening is to be made out. The principal thickening is 

 on the inner walls. 



Tubercles on the Roots of Leguminosse.| — Herr J. Brunchorst 

 contests the view of Woroniu and Eriksson that the rod-like bodies 

 found in these structures are bacteria, connected genetically with the 

 fungus-hyphre which are also frequently found in them. He has 

 frequently found them where the hyphse were entirely wanting ; and 

 has also found on the hyphaa a formation of spores altogether differing 

 from the bacterium-like bodies. These he regards as simply 

 albuminoid particles separated from the normal protoplasm of the 

 root, and proposes to call them hacteroids. 



This view is confirmed by the facts that there is no evidence of 

 the entry of any parasite into the root, and that the bacteroids have 



* Preuss, P., ' Die Beziehungen zwischen d. anat. Bau u. d. phys. Function 

 d. Blattstiele u. Gelenkpolster,' 58 pp., 8vo, Berlin, 1885. See Bot. Centralbl., 

 xsiv. (1885) p. 297. 



t Arch. Ne'erland. Sci. Exact, et Nat., xx. (1 pi.). See Bot. Centralbl., xxiv. 

 (1885) p. 326. Cf. this Journal, iii. (1883) p. 383. 



X Ber. Deutsch. Bot. Gesell., ill. (1885) pp. 241-57. 



