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FLUID PARTS OF VEGETABLES. 
ting the roots and stems horizontally, greater resistance is to be 
overcome, since the tubes are to be divided or cut across. 
Vegetables like animals have a system of glands , or internal 
vessels which are by the author of nature made subservient to 
the purpose of producing changes in the fluids of the plants ; 
thus the sap is converted into the proper juices, and from the 
same soil and nourishment appear plants of very different prop- 
erties. 
Mirbel by the aid of the microscope succeeded in discovering a 
system of glands, in the pores of cells and on the borders of the 
spiral vessels. There are external glands which appear manifest 
to the naked eye ; as the nectaries of flowers, which secrete or 
manufacture honey ; and the stings of plants, which secrete an 
acrid substance, that by penetrating the skin causes a painful 
sensation. 
FLUID PARTS OF VEGETABLES. 
The different fluids which are exhibited in the vegetable body 
may be considered under three general divisions : 1st, the sap ; 
or ascending fluid ; 2d, the cambium or descending fluid ; 3d, 
the proper juices. 
The sap is a limpid, inodorous liquid, the elements of which 
are imbibed from the earth by pores in the radicles of the root. 
You know that if the earth around the roots of plants is depriv- 
ed of moisture, they soon die. Moisture furnishes to the radicles, 
water holding in solution various substances ; such as earths, 
salts, animal and vegetable matter. The radicles, by some un- 
known process, convert this fluid matter into sap, and then by 
means of vessels which form what is called the sap-wood or al- 
burnum., this sap ascends through the stems to the branches ; 
passing through the woody part of the petioles, and those mi- 
nute branches of the petiole which form the ribs and veins of the 
leaf, it enters into the vessels and cells which extend throughout 
its substance. 
The ascending sap is always in circulation, but its energy 
varies with the season and the age of the plant. Heat has an 
important influence upon the ascent of the sap ; yet during a 
dry and hot season it often appears to ascend but slowly. This 
is owing to the absorption of fluids from the earth, being check- 
ed by the dryness of the soil. The plant may by a little stretch 
of the imagination, be considered as thirsty, and thus man may 
seem not only provident, but humane in administering to its roots 
refreshing draughts of water. Even the leaves seem at such a 
Glands of vegetables — their use — Nectaries of plants — Fluids — Three 
divisions — Sap — From what imbibed — Alburnum. 
