140 The Botanical Gazette. 
obtained from them. The theory of assimilation, given by 
Baeyer, which assumes that formic aldehyde, being the firt 
product of assimilation, is the origin of the carbohydrates — 
has been supported by the fact established by Bokorny’, that 
sodium-oxymethylsulphonic acid could supply the amount of | 
carbon wanted by Spirogyra. 4 
~ All the natural pentoses so far known belong to the /-series : 
and all the natural hexoses to the @-series. Plants by assifik 
lation either form hexoses and pentoses, or have the pow 
to change d- into /-compounds. The theory of Baeyer, does 
not make it improbable that both pentoses and hexoses #* 
formed. This work was undertaken to determine the limi 
of the reactions. Soluble pentoses which could be identified 
as wandering substances were sought. 
It was possible in all cases which were examined to show 
the presence of soluble substances which form furfurel 
these substances might be hexoses which furnish traces® 
furfurol. On this account it was necessary to estimate ™ 
much furfurol the hexoses which were present could form a 
how much in fact was formed. : 
For the estimation of small amounts of furfurol @ met 
was devised which depended on_ the color reaction | 
furfurol and an acetic acid solution of aniline. It was P ae 
that the amount of hexoses present was not sufficient "a 
plain the formation of all the furfurol and therefore per 
pentoses were present. Leaves and colorless bark ee 
for the experiments. The soluble pentoses are me gir 
fusible through membranes. The fact leads to the © 
sion that the soluble pentoses are simple sugars, C5 
The investigation confirmed the belief that the small 
of soluble pentoses is not perceptibly diminished by Oe 
of the leaves. In the leaves of the oak there was f ' 
the evening a small but evident excess in the amount ‘5 
ble pentoses over that found in the morning. Joint a 
is the hypothesis that the soluble pentoses ar© for 
arily converted into stable forms directly after their 
tion by the process of assimilation. : the lo 
This paper forms a very important appendix - nts 
and fundamental paper by Tollens and his rials” 
1891 cited above. De Chalmot promises a further 
of his hypothesis. —J. CHRISTIAN BAY. 
a 
7Biologisches Centralblatt, xxu, September, (1892.) 
