64. 
MORPHOLOGY OF THE CELL. 
minutely, and has ascertained (as Lebreton also thought, see Husemann, Die Pflanzen- 
stofFe, p. 709) that they consist of Hesperidin. It is remarkable that only some indi- 
viduals of the species named yield sphere-crystals, as for instance those in the botanical 
garden at Würzburg ; a tree in the garden at Marburg yielded them in its unripe fruits 
in 187 1, but not since. Sphere-crystals of organic structure (combustible), but of 
otherwise unknown constitution, have also been described by Kraus and Russow; the 
former found them in the epidermis of the leaves and stem of Cocculus laurifoHus, on 
treatment of the fresh cells with alcohol, glycerin, or even water. Russow ^ found^_m 
the living cells of the petiole and mesophyll of Marattia cicutcpfolia and Angiopteris mmt&^ 
sphere-crystals which enclosed a small crystal or other minute body as a central nucleus. 
Where the living cells did not contain these structures, he obtained them by treatment 
with alcohol ; they left behind, on combustion, a considerable quantity of ash. Russow 
also found similar bodies in the cortex of Selaginella Martensii and in tropical orchids, 
when the plants had lain for some time in alcohol. He states that all these sphere- 
crystals have the property of staining with carmine. 
In the cell-sap of the Hepaticae there occur vesicles or nodules of a peculiar 
appearance. In a letter Pfeffer states that they are formed in the very young leaves 
of Jungermannieae {Alicularia Scolaris, Radula complanata, &c.) by the coalescence or 
grouping together of minute drops of oil, which are first formed in the cell-sap, not 
in the protoplasm, and must be regarded as products of excretion which have no 
further purpose in assisting growth ; as is the case also with the fatty oils which are 
stored up as reserve-materials. A membrane-like envelope surrounds these drops of 
oil, whose substance consists, in addition to oil, of water and small quantities of 
Proteids. Of a similar nature are the bodies found in the thallus of the Mar- 
chantieae, which, in the case of Lunularia, also contain tannin. 
Among other organised constituents of the cell-sap must be mentioned the spherical 
drops or granules containing tannin and surrounded by a thin membrane which are 
found in particular cells of the cortex of many plants rich in tannin, as Salix, Betula^ 
Alnus, Quercus, &c. (see Nägeli u. Schwendener, Das Mikroskop, p. 492). They are still 
more conspicuous in the motile parts of the leaves of the sensitive plant, where 
Pfeffer^ has investigated them with care. Here they consist of a thin but tolerably 
firm membrane, enclosing a concentrated solution which contains a large quantity of 
tannin. The strongly refractive contents of the spherical bodies are coloured blue by 
solutions of iron, and form a reddish-brown mass with potassium bichromate. If the 
contents are extracted with water containing alkali, acid, or alcohol, the membrane 
is left, and is perhaps what has been termed a ' pellicle-precipitate,' consisting of a 
combination of tannin with a proteid^ Pfeffer states that spherical bodies of 
this nature are found in particular cells of the cortex of the stem and petiole of 
the sensitive plant, as well as in the petioles of Oxalis stricta and Acetosella ; ac- 
cording to Meyen they occur also in Desmodium gyrans ; and, according to linger, in 
Glycyrrhiza. 
Sect. ii. Crystals in the Cells of Plants ^ — The crystal-like forms de- 
scribed in Sect. 7, in which proteids are sometimes found, though always mixed 
with other organic compounds, are not common phenomena, and must not be 
placed in the same category as the very abundant true crystals of lime salts now 
* Untersuchungen liber die Leitbündel kryptogamen, Petersburg, 1872, p. 109. 
^ Physiol. Untersuch., pt. I, Ueber Reizbarkeit, Leipzig 1873, p. 13 et seq. 
^ See Book III. Chap. i. Sect, i, Traube's artificial cells. 
* Sanio, Monatsber. der Berl. Akad., April 1857, p. 254.— Hanstein, ibid. Nov. 17, 1859. — 
Holzner, Flora, 1864, pp. 273, 556, and 1867, p. 499. — Hilgers, Jahrbuch für wiss. Bot. vol. VI. 
1867, p. 285. — Rosanoff, Bot. Zeitg. 1S65 and 1867.— Solms-Laubach, Bot. Zeitg. 1871, nos. 31-33. 
— Pfitzer, Plora, 1872, p. 97. 
