CHAP. XIII. 
CIRCULATION OP THE SAP. 
397 
parent and destitute of globules. Nevertheless, Link has 
unaccountably confounded with cinenchyma the turpentine 
vessels of Coniferge. {Elemental ed. 2., i. 196.) 
4. The latex itself originates in the sap, which rises by the 
tissue of the wood, and introduces itself into the foliaceous 
organs, thence, after being elaborated, passing into the bark, 
where it is deposited in the vessels in its mature form. De 
la Baisse caused a Euphorbia to pump up water coloured red ; 
the liquid ascended in the wood, reached the leaves, tinged 
the latex, and the colour spread from above downwards in 
the bark : but M. Schultz only twice succeeded, after many 
attempts, at obtaining this result. 
5. The function of the latex is to nourish the tissue among 
which it is found. Increase in the layers of wood and bark 
may be arrested, if by ligatures, or cutting off annular por- 
tions of the bark, the afflux of nutritious particles from above 
downwards is stopped. Now the latex is the only one of the 
fluids in the bark which can have a progressive motion, and 
it is therefore it which furnishes nutrition. Upon robbing 
Asclepias syriaca of a great quantity of its milk, it ceased to 
bear fruit, but it sustained no inconvenience upon merely 
losing its sap. In fact, the loss of only small quantities of 
latex injures plants very much. It is the phenomenon of 
autosyncrisis and autodiacrisis (attraction and repulsion of 
the globules) which produces assimilation and nutrition. In 
consequence of autodiacrisis, the molecules of latex escape 
through the sides of its vessels, to be conveyed to the parts 
requiring nutriment; while, on the contrary, autosyncrisis 
brings about the assimilation of the nutritious matter. In 
proof of which, it is found that the distribution of latex is 
most abundant in those parts where the greatest increase 
ought to take place, and that the rapidity of the cyclosis is 
greatest at the periods of developement, the temperature 
remaining the same. 
6. The cause of the motion may be assigned to heat ; for, 
when Acer platanoides was exposed to a temperature of — 18° 
to 24° centig. ( — 2° to 11° Fahr.), the latex ceased to move, 
but the motion was re-established when it was brought into a 
warm room: to endosmose; for water will sometimes cause a 
