398 BOTANICAL GAZETTE [NOVEMBER 
conclusion is reached that the seed deserves to be removed from Cardiocarpon, 
chiefly on account of its vascular structure, and therefore a new genus Mitro- 
spermum is proposed. Whether the seed belongs to Cordaites or not was not 
determined, for the platysperm character can no longer be used as an indica- 
tion of that group. Sections of unattached seeds must continue to be made, 
but there is far greater need of sections of attached seeds, for these will a 
solve the puzzling embryo situation attributed to paleozoic seeds.— .C. 
Phototropism.—NORDHAUSEN’ offers more evidence against the lens 
theory of phototropic perception. He finds that leaves of Begonia with killed 
epidermis assume the normal light position, the palisade cells being the per- 
ceptive organs. He says that ‘“‘the epidermis as well as its papillose character 
are not necessary for light perception.” He finds a great difference between 
the sensitiveness of the two halves of the leaves of Tropaeolum, which renders 
them unsuitable for comparing the effect of light on the wet and dry halves. 
This plant and method have furnished HABERLANDT with his best evidences 
for the lens theory. After offering this significant evidence against the theory, 
he states that HABERLAND?’s reply to his former criticism has not rendered 
that criticism any less applicable. He also holds that the evidence offered 
in HABERLANDT’s later papers is not of a sufficiently critical nature to give 
the theory any support.—WILLIAM CROCKER. 
Carbon dioxid as a fertilizer—A Berlin company has placed a product 
on the market known as ‘Germanol,’”’ which consists of an earthy mixture 
containing about 18 per cent calcinated soda. The company attributes the 
virtue of this mixture to an increased porosity of the soil following an increase 
in the proportion of carbon dioxid. ITSCHERLICH,” however, is of the opinion 
that if such a mixture has any value it must be attributed to the action of the 
carbon dioxid in increasing the solubility of various difficultly soluble soil 
substances. His comprehensive tests show that increasing the carbon dioxid 
content of the soil does not result in an increase of plant product; that there 
is always sufficient carbon dioxid in the soil to render mineral food available; 
that an increase in the carbon dioxid in the soil does increase the solubility 
of difficultly soluble substances, but that such increase is superfluous so far 
as any advantage to the plant is concerned.—RAYMOND H. Ponp. 
ophore of Selaginella——WorspELL” has used an investigation of the 
rhizophore of Selaginella as the basis of a discussion of the ultimate morpho- 
1s NORDHAUSEN, M., Ueber die Perzeption der Lichtsichtung durch die Blatt- 
spreite. Zeitschr. Bot. 2:465—506. 1910. 
%6 MITSCHERLICH, EILHARD Acne, Ein Beitrag zur Kohlensdurediingung. 
Landwirtsch. Jahrb. 39:157-166. r9gro. 
"7 WoRSDELL, W. C., The rhizophore of Selaginella. New Phytol. 9:242-253- 
figs. 2. 1910. 
