ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
469 
Crucifer® and allied orders — a soluble ferment possessing the properties 
of myrosin, and a glucoside analogous to potassium myronate. These 
principles are present in the largest quantity in the root ; but occur also 
in the stem and other vegetative organs of C. Papaya. They have 
nothing to do with the papaine and carpaine which have also been 
extracted from these plants. The properties of the seeds resemble those 
of the Capparidese : the myrosin is found only in the embryo ; the 
ferment only in the endosperm. 
Indican.* — rof. H. Molisch finds indican in about ten genera of 
plants belongi^ g to several natural orders, — Isatis, Polygonum , 
Phajus, Calanth •, Marsdenia , Indigofera , &c. It may be detected by 
exposing the part of the living plant which contains it, usually the root, 
to the action of vapour of alcohol ; the chlorophyll is then extracted 
by absolute alcohol, and the indican transformed into indigo-blue by 
the action of concentrated chloral hydrate. Indigo-blue never occurs in 
the living cell. 
In the rhizome of Lathrsea squamaria he finds a colourless chromogen, 
yielding, with dilute hydrochloric acid, a blue pigment which is cer- 
tainly not identical with indigo. 
Pigment of the Aril.f — Bitter Schrotter v. Kristelli has investigated 
the nature of the pigment contained in the aril of Afzelia Guanzensis 
(Leguminosae) and Bavenala madagascariensis (Musaceae), and finds it 
(in the first-named plant) to be a lipochrome identical with carotin, 
combined with a fatty oil. The pigment of the aril of Bavenala is of a 
totally different character, and differs in some respects from any hitherto 
found in the vegetable kingdom, though presenting some analogies with 
indican. The structure of the seed, of the aril, and of the funicle, is 
described in detail in each case. 
Nitrates in Living Plants.! — M. Demoussy explains the absence of 
nitrates from dead roots and from withered leaves, by the fact that in 
living tissues their extreme solubility is counteracted by their entering 
into a very close mechanical association with protoplasm. When re- 
leased from this they are again readily dissolved out by water. 
(3) Structure of Tissues. 
Connection between Lignification, Firmness, and Elasticity in 
Cell-walls. § — From experiments made on a number of woody plants, 
Herr P. Sonntag derives the law that there is an inverse relationship 
between lignification aud increase in diameter. Tissues which consist 
of cells that are but little or not at all lignified offer a much greater 
resistauce to traction than those which are greatly lignified. The degree 
of elasticity stands in an inverse, that of extensibility in a direct, relation 
to lignification. 
Increase in Thickness of the Stem of Monocotyledons.|| — From 
an examination of the stem of about thirty species of Monocotyledons, 
* SB. K. Akad. Wiss. Wien, cii. (1893) pp. 269-90. 
f Tom. cit., pp. 381-421 (2 pis.). 
j Comptes Rendus, cxviii. (1894) pp. 79-82. 
§ Landwirthsck. Jalirb., 1892, pp. 839-69. See Biol. Centralbl., xiv. (1894) p. 138. 
|| Bot. Tidsskr., xviii. (1893) pp. 112-26 (12 figs.). See Bot. Centralbl., lvii. 
1894) p. 388. 
1891 2 K 
