90 
POPULAR SCIENCE REVIEW. 
Vines and Mr. Bennett agree that it is incorrect to place the Characece 
among the Carposporece , since they have stronger affinities with the mosses, 
with which the latter proposes to unite them. In this view, however, Mr. 
Vines does not concur. He holds a that a well-marked alternation of genera- 
tions occurs in the life-history of the Char a, and that the Char a- plant with 
its reproductive organs is the oophore, the sporophore being represented by 
the embryo — i.e ., the product of the development of the central cell of the 
archego nium. In order to indicate the fact that no spores are ever produced, 
so far as is at present known, by the sporophore of Char a, we may speak of 
this plant as being 1 aposporous,’ using a word which is symmetrical with the 
term ‘ apogamous,’ applied by Be Bary to those ferns in whose life-history 
no process of sexual reproduction occurs.” 
On the Kind of Light required by Growing Plants. — In the Comptes Rendus 
of November last M. Paul Bert gives the results of his experiments on the 
action of coloured light on vegetable life. He found that, while plants covered 
with green glass shades stopped growing and quickly died, those covered by 
panes of red glass continued to live and grow, though with diminished 
vigour. On submitting the coloured panes of glass to spectroscopic analysis 
with an illumination equal to diffused sunlight, he found that the red glass 
intercepted the yellow and all the more refrangible part of the spectrum, 
only the orange and red rays passing through, while the green glass per- 
mitted all but the least refrangible three-fourths of the red rays to traverse 
it. Hence it appears that the light essential to the continuance of plant 
life must be included in that portion of the red which is absorbed by the 
green pane. In order to further define its limits M. Bert compared the 
absorbent effect of the green glass with that of a dilute solution of chloro- 
phyll, which was found to stop only a small part of the red rays, namely 
those situated between B and 0. M. Bert then constructed a case with 
double walls of colourless glass, the space between the walls being filled with 
the chlorophyll solution, and it was found that plants kept in this case, 
though freely exposed to light, not only ceased to grow, but died as rapidly 
as those put under green glass shades. Thus the exact nature of the light 
rays indispensable for the support of vegetable life was determined, and it 
would appear (though proof is still wanting) that the regions of the 
spectrum capable of being utilised by plants are precisely defined by the 
various absorption-bands of chlorophyll. 
CHEMISTRY. 
The Crystallisation of Silicic Acid in the Dry Way. — In 1868 Vom Rath 
found on a specimen of trachyte a variety of silicic acid which differed both 
in form and density from quartz ; it was shown, in fact, that silicic acid, like 
sulphur, arsenious acid and antimonious acid can crystallise in tWo distinct 
forms. Ilautefeuille now finds that this compound can be crystallised arti- 
ficially in the dry way in these two different forms. Rose, who was the first 
to prepare the acid in the crystallised condition, obtained it, when a salt of 
phosphoric acid was employed in the form of tridymite. If amorphous 
silicic acid and tunorstate of soda be retained for a Iona- time at the fusing 
