PHYSIOLOGY. og” 
were put in a coloured liquid or mercury, by means 
of compression of the air. But not to mention the dan- 
ger connected with such experiments, the vessels can 
never be seen in their true form, as no doubt many 
of them must burst. ~The common method, then, 
of injecting them is by far preferable, though we 
are not in all plants equally successful with it. ‘The 
common ‘balsamime, (impatiens balsamina), is the 
plant best suited for such experiments. 
§ 233. 
Adducent vessels: (Vasa adducentia, moniliformica, 
succosa, propria, nutrientia vel fibrosa), ascend per- 
pendicularly, and are pretty large in most plants. 
As they are always in great numbers close below 
the cuticles, they appear, when the stems are cut 
through horizontally, in circles. In some young 
shrubs and trees, and in some of the more succu- 
lent herbaceous plants, they form ellipses, or tri- 
angles, pentagons and hexagons. ‘They serve in ve- 
eetables the same purpose as arteries in the animal 
body. ‘They are commonly quite straight, and 
consist of links, which are somewhat contracted, 
of which each has at its upper and under part little 
prominent margins, leaving, however, an opening 
from one link to the other. The inner surface of 
these links or vesicles, as we may call them, is 
covered ‘with soft slender hairs, which when the 
ressels get a more ligneous texture, closely adhere 
to them, and make the surface very rough. 
Those links are of a different figure, and their 
form varies in proportion as the cellular texture 
Move 
