ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
759 
etiolated leaves contain a smaller proportion than those that are green ; 
while the reverse is the case with plants having a stem. The stems of 
etiolated plants contain a very small quantity of albuminoids. 
In a further series of experiments on the same plants * * * § the author finds 
no soluble carbohydrates present in etiolated leaves of Vida Faba ; and 
concludes that chlorophyll cannot be formed without the presence of 
sugar. The first chlorophyll in the leaves of germinating plants is 
formed at the expense of the sugar which is carried from the seed by the 
transpiration-current. Iron is also necessary to its formation. 
Quantity of Starch contained in the Radish, f — M. P. Lesage finds 
that although, under normal conditions, the radish contains no, or but 
very little, starch, yet if the seedlings are watered with water containing 
sodium chloride in solution, a very considerable quantity of starch is 
formed. The optimum proportion of salt in the water was found to 
be 4 gr. per 1000; a second lower maximum occurred with 10 gr. 
per 1000. 
Tannoids.J — M. L. Braemer gives an account of the present state of 
our knowledge, chemical and physiological, of the products of metastasis 
grouped under the name of tannins. He regards the group as a very 
heterogeneous one. None of the reactions relied on for the diagnosis of 
tannins are common to all substances included under that term, nor are 
they limited to them. Our present knowledge of these substances is, in 
fact, very imperfect. 
Crystals of Calcium oxalate. § — Recurring to the question of the 
form in which calcium oxalate occurs in the tissues of plants, Prof. G. 
Arcangeli now states that in some cases single crystals belong to the 
monoclinic, and not to the dimetric system. The clusters of crystals are 
most often monoclinic, rarely dimetric. In the former case the crystals 
are frequently arranged radially round a central point, and present 
often a different structure in their internal to that in their external 
portion, the former having a more radiate, the latter a more crystal- 
line appearance. An organic nucleus could not be detected. 
(3) Structure of Tissues. 
Anatomy and Physiology of the Conducting Tissues. || — M. A. Gravis 
divides his treatise on this subject into three sections : — (1) Morphology 
of the Wood. The development of the xylem in the stem and root is 
followed out in detail, taking TJrtica dioica as an example ; the variations 
in the composition of the xylem are then described in four different type- 
plants, Polypodium ramosum , Pinus sylvestris, Quercus robur , and Trades - 
cantia virginica. (2) Physiology of the Wood. The theory of the circula- 
tion advocated by Bohm is adopted, and the bordered pits are treated as 
* Ber. Deutsch. Bot. Gesell., ix. (1891) pp. 229-32. 
f Comptes Rendus, cxii. (1891) pp. 373-5. Cf. this Journal, ante , p. 625. 
X ‘ Les tanno'ides,’ 8vo, 154 pp., Toulouse, 1890, 91. See Bot. Centralbl., xlvii. 
(1891) p. 274. 
§ Nuov. Giorn. Bot. Ital., xxiii. (1891) pp. 489-93 (1 ph). Cf this Journal, ante, 
p. 616. 
l| Mem. Soc. Beige Microsc., xii. (1889) pp. 87-118 (2 pis.). See Bot. Centralbl., 
xlvii. (1891) p. 241. 
