()58 SUMMARY OF CURRENT RESEARCHES RELATING TO 



division of the reduction-nucleus gives rise to the first two cells of the 

 gametophyte ; the daughter-nuclei go into a resting stage, and form a 

 network from which a new spirem is developed. The chromosomes are 

 distinctly V and U-shaped. 



Permeability of the Walls of Tracheids for Atmospheric Air.*— 

 P. Claussen discusses this subject from a mathematical point of view, 

 and, notwithstanding the great difficulties of the problem, from the 

 possible occurrence of very minute fissures, comes to the conclusion that 

 moist tracheid-walls are more permeable than dry ones fur atmospheric 

 air. liarefaction of the air can exist only for a short time in the water- 

 conducting elements after the cessation of suction (root-pressure). The 

 density of this rarefied air varies between 0'5 and 0*9 atmospheres. 



Fixation of Metals by the Cell-walLf — H. Devaux finds that all 

 metals with strong basic properties — potassium, sodium, lithium, calcium, 

 strontium, barium, iron, nickel, cobalt, cadmium, copper, lead, silver — are 

 absorbed in appreciable quantities by the cell-wall, even from very 

 dilute solutions, especially by the soft tissues. Gold, platinum, chro- 

 mium, were not absorbed, and mercury scarcely. With zinc, manganese, 

 magnesium, and aluminium, sufficiently delicate reactions have not been 

 discovered. A metal fixed in this way may be replaced by another metal 

 presented in the form of a saline solution. 



(2) Other Cell-contents (including' Secretions). 



Albuminoids of the Seeds of Leguminosse4 — According to K. 

 Weiss, the phosphorus which is an' invariable accompaniment of albu- 

 men in plants depends partly on the presence of lecithin, partly on that 

 of nuclein. Globulin is split up by various agencies into albuminates 

 containing phosphorus or into casein and hetero-albumose. Vegetable 

 globulins must be regarded as saline compounds of inorganic bases and 

 an acid albumen, which, when freed from the base, splits up into casein 

 and hetero-albumose. In the same way, vegetable albumins are saline 

 compounds of bases and an acid albumen, which, wheu freed from the 

 base, forms casein. Inorganic bases play therefore an important part 

 in the albuminoid processes. The globulins of the seeds of Legumiuoste 

 are indefinite mixtures of proteids closely resembling one another. They 

 belong to a homologous series beginning with hetero-albumose and pass- 

 ing, through the globulins, into albumose. 



Yellow Colouring Matters of Leaves.§ — C. A. Schunck has made 

 further spectroscopic observations on the yellow colouring matters which 

 accompany chlorophyll in the leaves of plants. His conclusion is that 

 chrysophyll (the orange xanthophyll of Sorby) pre-exists in the leaf, 

 and is not formed spontaneously from one of the other colouring matters, 

 and that it is one, if not the chief, constituent of the xanthophyll group 

 of yellow colouring matters which accompany chlorophyll. In one 

 point he revises his previous conclusion, and now believes that the four- 



* Flora, lxxxviii. (l!)01) pp. 422-69 (9 figs.). 

 t Comptes Rendus, cxxxiii. (1901) pp. 58-130. 



X Ueb. d. TCiweissstofi'e d. Leguminosen-Samen, Mimchen, 1899, 3G pp. See Bot. 

 Centralbl., lxxxvii. (1901) p. 13. 



§ Pmc. Hoy. Soc, lxviii. (1901) pp. 474-80 (2 pie.). Cf. this Journal, 1899, p. 611. 



