ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 251 



Structure of the root and arrangement of the rootlets in Centro- 

 lepideae, Eriocauleae, Juncese, Mayacese, and Xyridese.*— M. P. Van 

 Tieghem states that the structure of the root and arrangement of the 

 rootlets have been frequently studied in Gramineae and Cyperaceae. In 

 this paper the author describes these features in some of the other closely 

 allied monocotyledonous groups. He concludes by stating that the 

 anomaly of having the pericycle of the root regularly interrupted outside 

 the woody bundles, and of forming in consequence the rootlets, opposite 

 the liber-bundles, has been observed up to the present in seven families 

 of Monocotyledons, namely, Xyrideae, Mayaceae, Junceas, Eriocaulere, 

 Centrolepideae, Cyperaceae, and Gramineae. 



Geminate Root-hairs. f — M. P. Van Tieghem states that occasionally 

 a differentiation takes place in the piliferous layer of the root, the root- 

 hairs undergoing a special grouping which merits attention. In the 

 root of Pcepalanthus the piliferous layer is composed of both long and 

 short cells. The short cells, which are tabular in form, are sometimes 

 prolonged directly into hairs, but more often they are divided into two 

 halves by longitudinal septa. These two sister-cells then develope 

 towards the exterior into two hairs, which diverge in the form of a V. 

 This arrangement may be met with more especially in certain Eriocauleae 

 and Junceae. 



Root-tubercles of Leguminosse.ij: — Dr. O. Mattirolo and Sig. L. 

 Buscalioni have made a further examination of the nature of these 

 structures, chiefly on various species of Vicia. They conclude, for the 

 following reasons, that the bacterium-like substances found in the cells 

 of these structures are not living bacteria, but bacteroids, protoplasmic 

 bodies endowed with brownian movement. Experiments on culture of 

 these bodies, under the most favourable circumstances, produced entirely 

 negative results. They broke up into smaller particles, which displayed 

 similar movements. Immersion for twenty minutes in boiling water did 

 not destroy this movement ; and they were unaffected by a temperature 

 of 130° continued for two hours, and by various antiseptics. The form 

 also is very variable : usually somewhat that of a Y with unequal 

 branches, but varying to that of an X, or exhibiting numerous branches. 



Tubercular Swellings on the Roots of Vicia Faba.§ — Prof. H. Mar- 

 shall Ward has succeeded in producing, by infection, the tubercular 

 swellings on the roots of a number of leguminous plants, especially on 

 Vicia Faba. He attributes their formation to hypertrophy of the tissue 

 caused by the attacks of an undetermined parasitic fungus, probably 

 belonging to the Ustilagineae. He was able to trace hypha3 of this fungus 

 penetrating through the whole length of a root-hair, and then traversing 

 the cortex of the root, piercing the cell-walls, at which spots they mani- 

 fest peculiar trumpet-like enlargements, and branch when they reach the 

 tissue of the young tubercle. In addition to the hyphse which traverse 

 the cell-cavities, there are always found minute corpuscles suspended 

 in the protoplasm of the cells. These Prof. Ward believes to be gemmae 

 or bud-like outgrowths from the hyphae ; the fungus having lost its 



* Morot's Journ. Bot., i. (1887) pp. 305-15. 

 t Ann. Sci. Nat., vi. (1887) pp. 127-8. 



t Malpighia, i. (1S87) pp. 404-74, 536-41. Cf. this Journal, 1887, p. S87. 

 § Phil. Trans., clxxviii. (1887) pp. 539-62 (2 pis.). Cf. this Journal, 1887, 

 p. 1005. 



