CHAP. XIII. 
CIRCULATION OF THE SAP. 
399 
very long meshes, in which are perceptible currents of latex 
ascending, descending, and returning upon itself. Besides, 
at the side of the focus, in the cellular tissue, we remark the 
cyclosis in distant currents, and the same thing is visible 
between the cells of the hair. It is observed that the 
scattered currents, whether in the cellular tissue of the stem, 
or in the hairs, are neither separate in each cell nor isolated 
throughout the cellular tissue, but united to the focus of 
circulation in certain places ; so that all the latex circulating 
in the cellular tissue and the hairs is derived from the focus 
of the cyclosis. The same things are still more distinctly 
visible in Campanula rapunculoides. 
The great cause which has prevented naturalists from 
recognising the truth of M. Schultz’s discoveries has, doubt- 
less, been the extreme difficulty of observing a vital pheno- 
menon so easily stopped as that of cyclosis ; for if vessels are 
wounded, and it is an operation of great delicacy to avoid 
injuring them, in preparing their slices for microscopical 
examination, the motion ceases. Nevertheless, it may found 
with tolerable facility in the stipules and bark of the Fig, 
especially of Ficus elastica; in the leaves, and even the 
valves of the fruit, of Chelidonium ; and in the bark of Acer 
platanoides. In no case, however, is it seen more easily 
than in the interior sepals of Calystegia sepium, which are 
thin enough to bear examination, without laceration, when 
viewed by transmitted light. In the larger vessels (vasa ex- 
pansa) the latex appears stationary ; but in the smaller ramifi- 
cations it is seen to move rapidly or slowly, by starts or in a 
steady current, carrying along with it single globules or several 
together, which are forced along the passage in the vessels, 
much as pieces of wood might be expected to be carried in 
water through a narrow and sinuous channel. It looks as if 
the matter of the latex met with frequent obstructions, which 
stopped the current for a moment and then gave way, when 
a rapid flow goes on till it is again interrupted. Professor 
Morren has also mentioned the young flowers and receptacle 
of the common Fig, as an extremely easy subject in which to 
find the motion. 
