396 
PHYSIOLOGY. 
BOOK II. 
even scattered cords. Vessels of latex may even be found 
in the pith. Schultz finds them in communication with the 
curious glands which in Nepeilthes line the pitcher, and 
secrete the water found therein. In the form of capillary 
vessels (vasa contracta), they are very commonly present in 
hairs, where they form a most delicate plexus. It is, how- 
ever, difficult to prove that the streams visible in hairs are 
really ramifications of cinenchyma, and Meyen has even 
denied their existence, upon which M. Schultz says with 
some asperity : Wonderful enough, he has had them before 
his eyes, everywhere, in the fine anastomosing streams in 
which the sap circulates in the cells, without recognising 
them. These vessels pass through and round the different 
organs, particularly the cells of the secreting organs, like a 
fine spider’s web, and are visible in many plants, for example 
in the species of Caladium and Arum, even after maceration.” 
3. The latex is a highly elaborated and highly organised 
juice, which is not formed immediately from the fluid nu- 
trient matter absorbed from without. It is usually viscid, 
insoluble in water, often opake, coloured white, yellow, red, 
brown, and is also often transparent and colourless ; differ- 
ences that result from the nature of the organised globules 
it contains, which, according to M. Schultz, constitute the 
living part of the latex. These globules have an oscillating 
motion, and, like the globules of blood, they coagulate, and 
the liquid part becomes transparent. In many plants wdiich, 
when old, have a milky latex, it is colourless when they are 
young ; this depends upon the degree of concentration of the 
latex. Upon exposure to the air, latex separates into a 
coagulum of a tenacious elastic quality, and a serum, the 
former being sometimes analogous to caoutchouc. This pro- 
perty is not found in any other vegetable secretions. If we 
consider the organisation of the latex, the globules it con- 
tains, its property of coagulating and separating into serum 
and a sort of fibrine, we are tempted to believe that there 
exists a considerable analogy between it and the blood of 
animals. By these marks the latex may be known from 
ethereal oil, resin, gum, and other secretions sometimes found 
in the interior of parenchyma, and which are always trans- 
