Page:Proceedings of the Royal Society of London Vol 4.djvu/475

Rh the former of a portion of its water by the sudoriparous glands of the skin on the one hand, and by the lymphatic vessels on the other.

That the separation of the lymph from the blood is calculated to increase its density, is proved by its chemical analysis ; lymph con- taining from 96 to 97 per cent, of water, and blood from 77 to 82 per cent. The author regards this separation of lymph from the blood as the result of a purely vital process of the same nature as that by which the saliva and the watery portion of the urine are secreted from the circulating mass. He considers that his views are supported by the anatomical distribution of the lymphatic system : for, on the principle that organs are found in the vicinity of the places where their office is wanted, the office of the lyphatics must be general, inasmuch as the system is general. These vessels may, in fact, be regarded as the essential element of an universally dis- tributed gland. The mode in which the lymphatics are finally con- nected with the blood-vessels appears also to indicate that the object in view is to keep th^ir watery fluid separate from the blood as long as possible ; for, as is well known, they do not transfer their contents into the neighbouring veins, but pour their whole fluid into the superior vena cava at the moment it is about to enter into the heart.

The remnrkable manner in which the lymphatic system is de- veloped in some of the lower tribes of animals, whose bodies are en- cased in an impervious horny covering, such as turtles, lizards and serpents, is adduced in further corroboration of the author's views. He regards the serous membranes as contrivances for the accom- modation of a great number of lymphatics; and the intimate con- nexion which the function of these vessels has with the life and nutrition of internal organs he thinks is shown by the remarkable amount of disturbance consequent on inflammation, or other morbid condition of serous membranes. Finally, the author adverts to the influence which the difference of endosmotic capability engendered by the abstraction of a certain amount of water in the course of the circulation, (first between the blood corpuscles and the plasma in which they swim, and then between the liquor sanguinis and the containing channels,) must have on the capillary circulation, which he conceives it is calculated to facilitate.

2. " Further Observations on the descending fluids of Plants, and more especially the Cambium." By George Rainey, Esq. Com- municated by P. M. Roget, M.D., Sec. R.S.

The author relates an experiment in proof of the sap descending from the upper to the lower part of an exogenous tree, through vessels which are continuous from the leaves to the roots ; the course of these vessels being shown by the addition of a solution of iodide of potassium after they had taken up by absorption a quantity of a solution of acetate of lead. The fluids in these vessels arc, he con- ceives, separated from the sap, which is ascending from the roots, only by the membrane of which they are composed. When the leaf-buds of a tree ai-e vegetating, large separations are observable