38 INTRODUCTION TO BOTANY. 
posed of an elastic membrane rolled up like the spring of 
a bell into a cylinder, abundant in young shoots; supposed 
to convey air. PI. 1. fig. 5.1. ae 
a. 4. Mixed vessels, Vasa mixta. Tubes of a mixed 
nature, in some parts dotted, in others streaked or spiral. 
b. Vasa adducentia spiralia, Vasa chymifera, Vasa hydro- 
Ae The spiral thread forming the air vessels; consi- 
ered by Hedwig as a distinct species of vessels itself. 
c. Proper vessels, Vasa propria, Receptacula sucet proprii. 
Cavities dispersed in the cellular texture, closed on all 
sides, and filled with some peculiar juice. 
c. 1. Bladdery reservoirs, Receptacula vesiculosa, Glan- 
dule vesiculares. Spherical bladders, usually contain essen- 
tial oils, dispersed in the parenchyme of the leaves, or 
‘bark. .Myrtus communis, Citrus Aurantium. 
c.2. Blind reservoirs, Receptacula ceeciformia, Vitte. 
Short tubes, filled with essential oils, as in the bark of the 
seeds of umbelliferous plants. 
c. 3. Milk vessels, Turpentine vessels, Receptacula tu- 
bulosa, Vasa propria solitaria. Single tubes in the cellular 
texture, filled with a milky, or turpentine juice. 
c. 4. Fascicular reservoirs, Receptacula fascicularia, Vasa 
propria fascicularia. Bundles of small parallel tubular 
cells, filled with a peculiar juice; as in the bark of apo- 
cinez. 
c. 5. Accidental reservoirs, Receptacula’ accidentalia. 
Accidental cavities, into which the juices formed in other 
parts has filtrated: in the coniferze the turpentine frequently 
bursts its own vessels, and penetrates the pith and sap- 
vessels. 
Tubular openings. Open spaces of the pith, Lacune, 
Cavitates aéree, Vasa pneumaiica, Receptacula aérea acci- 
dentalia. Cavities filled with air, frequently found in the 
cellular texture, formed by rupture or absorption. 
1, Irregular, L. trregudares. Found in the middle of the 
fleshy parts of plants. Pl. 1. fig. 5. k. | : 
2. Vistular, L. fistuiose. Occupy the centre of the stalk, 
and render it hollow like a flute. Graminexe. _ 
3. Regular, L. regulares. Occupy the centre of the stem 
of water plants, the cells being disposed in a regular order. 
Scirpus. 
4. Cellular, L. cellulares. Large cavities, of which the 
sides are themselves composed of cellular texture. Spar- 
ganium. 
