The Republican journal., 1874-02-12
VOLUME A.
Flow of Sap.

In the extensive and admirable series of
experiments and observations at the Mas
sachuselts Agricultural College at Am
herst, us detailed in the lecture of Presi-
dent Clark before the State Board Of Ag
rculture at Fitchburg, and designed to
ascertain the laws in relation to the flow
or circulation of sap in different species of
trees and plants it was discovered that
each species of those which flowed had its
own time of beginning, when it seemed
to awake from its winters repose; that
the flow steadily increased in quantity and
force, as indicated by the weight Of sap
and the pressure on a mecurial gauge, I'M
til it reached its maximum, and then
gradually declined and that the compost
tion of the sap Of the several species diff
tered remarkably. according to the date
OF the flow and especially the time OF its
beginning.
This singular periodicity. peculiar to
every species, demonstrates that the
absorption OF water by the rootlets is not
caused by osmose, or any other mere
physical force, but is the result OF the
specific life, which imparts to every plant
its distinctive characteristics.
The sugar maple begins to flow in Octo-
Der, reaches its maximum about the first
OF April, and ceases about the first Of
May. Mr.. H. s. Goodale, Of Mount Wash
ington, Mass. 4 member of the Board OF
Agriculture, states that he has made
maple sugar from sap collected in the
months OF October. November. January,
March, April and May The black birch
begins to flow the last OF March, attains
its maximum the last of April, and stops
about the middle OF May. The wild Sum-
mer grape vine commences about the first
Of May, arrives at its maximum of flow
and pressure about the Goth OF May, and
ceases early in June
This difference in the season Of flowing
is, of course, accompanied by q CORE
spending variation in the temperature OF
the soil and the atmosphere, and very
naturally also in the chemical composition
OF the sap. Thus the principal ingredient
of maple sap is cane sugar, that OF birch
say is grape sugar, and that of vine sap is
mucilage or gum.
These three carbohydrates. cane sugar,
grape sugar and gum, are doubtless chief
" formed out of the starch which has de
scended to the root of the plant as the re
suit of the previous seasons growth. 1t
occur in the sap after the period OF activity
begins and in the following order, viz;
Insoluble starch, whether deposited in the
cells of the root or previously transferred
in solution to those of the stem, and there
stored during the period Of repose, be
comes soluble gum, gum becomes uncrys-
tallizable grape sugar, and this under
favorable circumstances becomes cane
sugar. Why then do we find cane sugar
i'll the maple and not in the Birch and why
only gum as the chief ingredient in the
sap of the vine, and Of those trees which
do not acquire the power Of active alb
sorption until the development OF their
buds Probably because these transfor-
nations require time, and the maple alone
is gorged with sap during the six months
interv ening between the fall of the leaf
and the beginning of growth in the spring
This affords ample time for chemical
changes, and seems to have some connec-
ton with the fact that the naples are the
only trees from which clystallzahle cane
sugar can he protitably extracted
For Il similar reason, since we find the
birches filled with sap ion several weeks
before Il bud begins to expand, we may
reasonably expect the formation of grape
sugar at least in them, and in the north OF
Europe a sweet syrup is obtained hy the
evaporation of their sap.
The spring sap OF the Vine At the begin
ming of its motion, about the first OF May,
contains no sugar Of any kind, but three
weeks later it often acquires a sweetlsh
taste and then we may find a trace Of
grape sugar. At this period the begin
ming of vegetable growth is attended by
the rapid eXhalation Of the water OF the
crude sap, and the assimilation Of lis gum,
in the formation Of cellulOSe, and this is
precisely the transformation which ordi-
narily occurs in plants al the beginning Of
the Vegctating season,