Essays on the Microscope / Containing a Practical Description of the Most Improved Microscopes, a General History of Insects, etc., etc.

by George Adams

OF THE VASA PROPRIA INTERIORA.

Besides the lymphatic vessels and the cellular substance, we find the juice vessels, or vasa propria, in the bark. In those trees which are famous for medicinal virtues, they are usually very large; they carry the milky juices of the sumach, and in them is lodged the finest and highest-flavoured turpentine in all the kinds of pine. Dr. Hill thinks that a tree of that genus exhibits them best, and the more, as the turpentine which fills them may be perfectly dissolved in spirit of wine. The pinus orientalis is the species in which these vessels are most distinctly seen.