292 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
only under double refraction. The author criticises the views of Nageli, 
Meyer, and Biitschli, respecting the nature of the swelling. 
Inulin is especially characteristic of the Composite, occurring in most 
of the tribes and a large number of the genera of that order. It is found 
also in the allied orders Campanulacese, Lobeliaceae, Goodeniacere, and 
Stylidiaceae, and occasionally elsewhere ; very rarely in Monocotyledons. 
Its presence has been recorded in Algae, but not certainly in Gymno- 
sperms, Pteridopliyta, Bryophyta, or Fungi. There is only one instance 
of its occurrence in an annual plant. Its main function is undoubtedly 
that of a reserve food-material in the dormant period, especially in the 
underground organs. 
Proteolytic Enzyme of Nepenthes.* — Further experiments by Prof. 
S. H. Vines lead him to confirm his previous statement of the remarkable 
stability of the enzyme of the pitcher-plant. It is in all probability 
derived from a zymogen present in the gland-cells. The enzyme is 
essentially tryptic in its character — this may be a characteristic feature 
of all vegetable proteolytic enzymes — and closely resembles that of the 
germinating seed, but is more rapid and energetic in its action, and more 
stable in its nature. 
Presence of Simple Organic Compounds in the Vegetable Kingdom.! 
— -Herr A. Lieben claims to have determined the presence in plants 
(grass and the leaves of trees) of formic and acetic acids, and of a higher 
fatty acid, probably propionic. The neutral products isolated were 
methylic and ethylic alcohols. 
Presence and Function of Silica in Plants.^ — In the case of cereal 
crops, Herr V. v. Swiecicki states that the upper portion of an internode 
is always firmer than the lower portion, in consequence of containing a 
larger amount of silica. The greatest degree of firmness was found in 
the first and the fifth internodes. The upper part of the fifth internode, 
in particular, contains a proportion of silica much above the average. 
Copper in Plants. § — According to Prof. D. T. MacDougal, copper 
is an element of very wide distribution in plants, and, in very minute 
quantities, does not appear to have an injurious effect on them. It occurs 
in the form of finely divided reddish-brown particles in the tracheids, 
vessels, and medullary parenchyme. 
(3) Structure of Tissues. 
Structure of the Wall of Vessels || — According to Herr W. Rothert, 
the ordinary classification of vessels into spiral, annular, reticulated, and 
those with bordered pits, rests on an erroneous view of their origin. The 
essential structure of the membrane is the same for all vessels ; all kinds 
of vessels are characterised by the presence of bordered pits. These can 
be classed under two principal heads, according as they are extensible 
* Ann. of Bot., xii. (1898) pp. 545-55. Cf this Journal, 1898, p. 207. 
t Monatsschr., xix. (1898) pp. 333-54. See Journ. Chem. See., 1899, Abstr., 
pt. ii. p. 45. 
X Die Bedeutung d. Kieselsaure u. s. w., Halle a. S., 1898, 45 pp. See Bot. Cen- 
tralbl , Beih., viii. (1899) p. 288. § Bot. Gazette, xxvii. (1899) pp. 68-9 (1 fig.). 
|| Bull. Internat. Acad. Sci. Cracovie, C.R., 1899, pp. 15-53 (2 pis. and 7 figs, in 
Polish original). 
