638 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
clary increase in thickness of the extine of the pollen-grains of Althaea 
and Knautia is attributed to a secondary imbibition of living protoplasm 
rather than to the original presence of protoplasm. In these pollen- 
grains the extine is double, the two layers being separated by a rod- 
layer ( StdbchenschicJit ) ; the rods are free, but the spaces between them 
may be filled by soluble pigments. Similar “rod-layers” unite also 
the more strongly refractive layers of the membranes of the pith-cells in 
Clematis , and possibly occur in all stratified membranes. The author 
finds that the thick-walled strongly lignified pith-cells of Clematis are 
still caj)able of division. 
(2) Other Cell-Contents (including- Secretions). 
Active Albumin in Reserve-material.* * * § — Out of 48 species of trees 
examined, M. U. Suzuki finds, in 25, active albumin in the cortex, and 
more abundantly in the cortex than in the buds. He concludes that 
active albumin acts as a reserve-material, being stored up in the winter 
and used up in the spring in the formation of the buds. 
Spheroids and Crystalloids in Phytolacca.f— Herr 0. Kruch de- 
scribes these structures especially in the apex of the leaf of P. icosandra , 
which runs out to a sharp leathery yellowish point, and in other species. 
They are large round usually colourless strongly refringent structures, 
and occupy a large space in the protoplasts. They are usually homo- 
geneous, but sometimes contain one or more vacuole-like cavities. 
Similar structures were observed in the apex of the leaves of P. abyssi- 
nica , where there is either one in each cell in the neighbourhood of the 
nucleus, or a number of small ones, often united into clusters. 
Tannin-like Drops in the Cell-sap of the Leaves of Bromeliacese.f 
- — In the parenchyme-sheath of the vascular bundles of the leaves of Bil- 
ler gia amcena, Dr. G. S. Wallin finds peculiar very refringent yellow to 
yellow-green or yellow-brown drops in the cell-sap of all the cells. In 
each cell is usually one relatively large (16-18 /x) or several smaller 
drops. The micro-chemical reactions are given, which determine these 
drops to be neither of a resinous nor of an oily, but of a tannin-like 
character. They are nearly or quite insoluble in the cell-sap, in which 
respect they differ from similar bodies in the Scrophulariacese, which are 
partially soluble. The presence of this substance is usually limited to 
the bundle-sheaths ; it was found in all species of Bromeliacese examined, 
and appears to be peculiar to that order. It is probably an excretion 
product. 
Distribution of Glutamin in Plants. § — According to Herr E. 
Schulze, asparagin is frequently replaced by glutamin as the soluble 
nitrogenous food-material of plants. It was found in 22 species belong- 
ing to 10 different families, among others Lepidium sativum , Baplianus 
sativus, Camelina saiiva i Spergula arvensis, Spinacia glabra , and Picea 
* Bull. Imp. Univ. Tokio, iii. (1897) p. 253. See Bot. Centralbl., lxxv. (1898) 
p. 199. 
t Ann. K. 1st. Bot. Boma, vii., 12 pp.-and 1 pi. See Bot. Centralbl., lxxv. (1898) 
p. 127. f Bot. Centralbl , lxxv. (1898) pp. 323-6. 
§ Landwirth. Yersuchs-Stat., 1898, p. 442. See Bot. Centralbl., lxxv. (1898) 
p. 200. 
