The Action of Chlorophyll in the Vine. By Giovanni Briost. 287 
Glucose, too, I have been unable up to the present to ascertain 
microscopically in the vine leaves, since I, once only, had precipi- 
tated some red grains of oxide of copper in but two cells; if 
afterwards there was found glucose, it was in such small quantity 
as to be totally insignificant. Of oil or fatty matter, either nothing, 
or an insignificant proportion, is found. 
The only substance, however, amongst those determinable by 
the microscope, which is met with in abundance in the vine leaves, 
is tannin. It is found not only in the epidermal cells without 
chlorophyll, on both sides of the leaf, but also in all the cells with 
chlorophyll ; nay, in the substance of the palissade (palizzata) cells 
of the upper part of the leaf, where, by the direct action of the 
light, the influence of the chlorophyll must be more energetic than 
anywhere else, tannin is most abundant. 
From this, and other observations, I will not conclude as yet 
that tannin is formed in the chlorophyll-grains of the vine leaf, 
well knowing how daring such a conclusion might appear, in- 
asmuch as the greater number of researches made with regard to 
the share held by the tannin substances in the vegetable economy, 
lead us to regard the tannin more than anything else as a secondary 
and lesser product, and one of those which, when once formed, 
change no more, and remain as inert substances in the cells in 
which they originated, without having any share in the formation 
of fresh organic substance. At any rate, from researches now 
undertaken, I hope soon to be able to say something more positive 
on this subject. 
One more observation: It is at present generally admitted that 
the libro tenero is made up of the texture which is destined for the 
carriage of the protein substances, whilst the hydrocarbons and the 
fatty matters would be conducted through the parenchyma. This 
theory originated with Professor Sachs (to whom vegetable physio- 
logy owes so much), and rests mainly on the fact that in the 
elements of the first texture only albuminoid substances are found, 
and because chemists never have been able to find starch, other- 
wise than in an exceptional manner, notwithstanding that the 
degree of these triple (threefold) substances can be so very easily 
ascertained. 
On another occasion * I have shown that in the libro tenero, 
and specially in the cribriform vessels, starch scarcely ever is want- 
ing, and even that this starch, on account of its most minute 
formation, and of the peculiar construction of the said organs, 
seems well adapted to be carried from one part of the plant to 
another. At present, it is not without interest to know that, in 
* Briosi, “Ueber allgemeines Vorkommen yon Starke in den Siebréhren” 
(‘ Botanische Zeitung,’ 1873, No. 15 and following ones); also ‘ Nuovo Giornale 
Botanico Italiano, April 1875. 
