ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
617 
(3) Structure of Tissues. 
Differentiation of the Endoderm.* — M. P. Lesago notes that in 
many plants (the bean, radish, &c.), the endoderm, especially of the 
root and of the liypocotyl, may possess a different structure, even in 
different spots of the same transverse section ; in one spot it may be 
suberized, in another spot amyliferous. As a general rule the cell-walls 
of the endoderm become more and more differentiated the greater the 
distance from the summit of the root; and in the same plant this 
differentiation may be manifested at very different distances from the 
summit, according to the mode of development of the root. 
Folded Tissue.! — M. P. Van Tieghem states that the endoderm of 
the root, and often of the stem and leaf, shows a more or less decided 
suberification or lignification of its membranes, strictly limited to one 
band on the lateral and transverse faces of its cells, and unaccompanied 
by any thickening. This has been termed by the author tissu plisse, 
and may occur in other regions besides the endoderm. Thus in the 
Coniferae and Cycadeae the piliferous layer of the root, which is of 
epidermal origin, is formed by this variety of lignified parenchyme. 
This is the first time that this tissue has been met with at the 
periphery. 
Secretory System of Papilionacese.J — Sig. P. Baccarini states that 
the secreting elements in the Leguminosae — which mostly contain 
tannin — form two principal systems in the branches and leaves, one of 
them consisting of tubular elements of greater or lesser length which 
accompany the xylem and the phloem of the vascular bundles in their 
course, the other consisting of idioblasts scattered among the cells of the 
cortex and of the parenchyme of the leaf. The xylem-tubes are always 
situated on the periphery of the pith ; those of the phloem occupy various 
positions, being often dispersed among the sieve-tubes. The greater 
number of Leguminosae are furnished with these tubes in both the xylem 
and phloem, though others have them in one or other only of these 
portions of the vascular bundles. Idioblasts occur in the cortex in most 
species examined. Those found in the parenchyme of the leaves 
either form a special layer in the spongy parenchyme, or are in imme- 
diate contact with the epiderm of both surfaces, forming a kind of sheath 
which incloses the mesophyll, or less often they are dispersed among 
the palisade-cells. A considerable number of Leguminosae are destitute 
of these secretory idioblasts. 
M. P. Yuillemin § criticizes several points in Sig. Baecarini’s paper. 
Tanniferous cells or tannocysts are but feebly developed, or are entirely 
wanting, throughout the tribes Genisteae, Yicieae, and Trifolieae ; the 
inconstancy of the characters of other tribes in this respect is often 
due to errors of classification ; or sometimes to the substitution of the 
tanniferous by some other secretory system, as, for example, by oxaliferous 
cells. The special structure of the tannin-cells is described in a large 
number of cases. 
* Comptee Rendus, exii. (1891) pp. 1522-3. 
f Journ. de Bot. (Morot), v. (1891) pp. 165-9. 
% Malpighia, iv. (1891) pp. 431-5; and Nuov. Giorn. Bot. Ital., xxiii. (1891) 
pp. 297-301. § Bull. Soc. Bot. France, xxviii. (1891) pp. 193-200. 
