ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
539 
ing from tlio ordinary leaves in being deeply incised, and tlie attacks of 
the parasitic fungus Exoascus Carpini which produces the “ witch- 
broom.” Particulars are also given regarding the biology of the 
parasitic fungus. 
Phyllodes of Acacia.* — M. G. Hochreutiner points out that, in one 
species of Acacia, A. leptospermoides, the leaf-like petiolo or pliyllode 
does not assume a vertical position, as is the case with all the other 
species, but has its two surfaces horizontal, like an ordinary leaf. The 
nectariferous gland does not occupy the margin, but is exactly in the 
centre of the upper surface. The author regards this as probably an 
archaic form. 
Laticiferous Hairs of the Cichoriacese.f — Dr. I?. Zander has 
investigated tho structure of the laticiferous hairs which are found 
on the involucre, and in some cases on the lower bracts, of many 
genera belonging to the Cichoriacese ; tho plants specially examined 
belong to Sonclius, Mulgedium, Lactuca , Prenanthes, Picris, and Lap- 
sana. These hairs burst by contact or concussion, and exude a drop 
of latex. The physical and chemical conditions prevent any further 
exudation after tho first drop, which rapidly oxidises and forms a solid 
substance closing the wound. The exudation is greatly promoted by 
a high temperature. The author regards the hairs as a very efficient 
protection against attacks of insects on tho adjacent reproductive 
organs. 
Hoot-Tubers of Isopyrum.J: — Prof. D. T. MacDougal gives the 
following as the main results of an examination of the root-tubercles of 
Isopijrum biternalum. The tubers are formed by an excessive develop- 
ment of the pericycle, which may accompany or follow the formation 
of the secondary tissues of the root ; this is associated with a tangential 
development of the cortex and endoderm and a radial development of 
the cambium. The first product of assimilation is probably cane sugar, 
which is converted, when used as a reserve-substance, into a form that 
stains reddish-brown with iodine. During the season of greatest ac- 
tivity a portion of the cane sugar is reduced into the form of “ red 
starch ” by the lcucoplasts which surround the nucleus. The tendency 
to form tubers on the roots seems fixed by heredity. The outer cortical 
cells of the roots and of tho tubers contain large drops of oil. 
The root-tubers of Isopijrum Occident ale are also described by the 
same author. § Their structure corresponds to those of I. hiternatum in 
its main features, with some noteworthy differences. 
Depth of the Underground Portion of Perennial Plants. ||— Accord- 
ing to Herr A. Kimpach, the required depth below tho surface of tho 
soil is acquired by the hibernating parts of plants in threo different 
ways : — (1) By the growth of tho underground portion of the stem 
itself ( Colchicum , Orchis, Paris , Pteris aquilina, &c.) ; (2) by the con- 
* Ann. Sci. Bhys. ot Nat., i. (189G) pp. 278-80. 
t Biblioth. lint., Heft 37, 1800, 44 pp. and 2 pis. 
j Minnesota Bot. Studies, 1890, pp. 501-1(5 (2 pis.). Cf. this Journal, 1804 
p. 587. § Bot. Gazette, xxi. (1890) pp. 280-2 (1 fig.). 
|| Ber. Dcutsch. Bot. Gesell., xiv. (189G) pp. 104-8. Cf. this Journal, 1895, 
p. 653. 
2 p 2 
