ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
205 
(2) Other Cell-contents (including" Secretions). 
Protein-crystals.* — Dr. G-. Stock lias investigated tlio mode of 
formation and the distribution of protein-crystals in a number of 
flowering plants, especially in the mature leaves of Achyranthes Ver- 
schaffeltii , the assimilating tissue of Bivina Jiumilis, the leaves of Syringa 
vulgaris and other Oleaceae, and the spongy and palisade-parenchyme of 
Veronica Chamsedrys . There are four modes of occurrence of protein- 
crystals — in the nucleus, in the chromatophores, in the cytoplasm, and 
in the cell-sap. The method employed was Zimmermann’s Method B, 
the staining reagent being acid-fuchsin. The more important results 
obtained are as follows : — 
In the plants where they occur protein-crystals are constant con- 
stituents of the normal nucleus, or of the normal chromatophores, cyto- 
plasm, and cell-sap. In the cases where they have been observed they have 
from the first a crystalline form, and do not owe their origin to pre- 
viously existing spherical structures. Those which are contained in the 
nucleus and in the chromatophores are not products of secretion ; they 
are dissolved and carried away before the death of the organ in which 
they occur. Light appears to have no considerable influence on their 
formation or on their persistence when formed. The protein-crystals 
of the nucleus and chromatophores disappear with a reduction of the 
amount of nitrogen in the nutrient solution, and are again formed on a 
fresh supply of nitrogen. In the plants examined the absence of calcium 
salts in the nutrient solution causes an accumulation of the crystals. 
In leaves of Bivina the formation of protein-crystals outside the nucleus 
was induced by the long-continued action of a nitrogenous nutrient 
solution. In a number of species of Oleaceae these crystals are very 
numerous in the bud-scales, and must be regarded as reserve-materials 
for the winter-buds. 
Crystallized Vegetable Proteids.f — Mr. T. B. Osborne finds crystal- 
lizable proteids in the following seeds: — brazil-nut, hemp, castor-oil 
plant, flax, squash. The composition of the crystallized globulins is 
given. These do not all coincide in chemical properties or in percentage 
composition. 
(3) Structure of Tissues. 
Length of Vessels and Distribution of Vessels and Tracheids. t— 
Herr A. Adler used for this investigation a solution of ferric oxy- 
chloride, which is a colloid, and cannot pass through membranes. If 
this solution is forced into a closed cell, all the iron is retained by the 
cell-walls, and pure water passes through. The iron can then be 
precipitated by ammonia. By this method he found vessels in the 
petiole of Pteris aquilina , but only tracheids in three other species of 
Pteris, and in all other ferns. In the primary and secondary xylem of 
Conifers he found nothing but tracheids. Vessels were detected in all 
Dicotyledons examined, and in all Monocotyledons except the root of 
Monster a Lennea and the species of Bromeliaceae examined. The vessels 
* Beitr. z. Biol. d. Pflanzen (Cohn), vi. (1892) pp. 213-35 (1 pi.). 
t Amer. Chem. Journ., xiv. (1892) pp. 662-89 (3 pis.). 
j ‘ Unters. iib. d. Langenausdehnung d. Gefassraume, u.s.w.,’ Jena, 1892, 56 pp. 
See Bot. Centralbl., lii. (1892) p. 128. 
