BOTANY. 3 
as the spores of certain aquatic plants, may have cilix or fine hairs, by 
means of which they can execute a progressive motion through the water. 
Under such circumstances, they have often been considered and described 
as infusorial animalcula. 
Pirrep Tissue (Bothrenchyma) is a modification of cellular tissue caused 
"by the unequal deposit of the thickening matter in the wall of the cell, 
leaving thinner portions, which, when viewed by transmitted light, appear 
like pores or pits. A spiral thread or fibre is sometimes found coiled up in 
the inside of the true cell wall, which, when the latter is dissolved, uncoils 
and exhibits itself in its true character. Such cells, called spiral cells 
(Inenchyma), are frequent in the orchidaceous and cactaceous plants. This 
fibre varies from zj55 to +,4s5 of an inch in diameter, and is solid, with a 
cross-section of various shape. The coils of the spire are sometimes 
broken up and recombined in various ways, so aS to appear as rings, 
reticulations, bars, or dots, thus producing annular, reticulated, scalariform, 
or dotied cells. 
Cells are sometimes aggregated so closely together as to leave no visible 
interspaces, the tissue being then termed perfect Parenchyma. Imperfect 
Parenchyma is where the cells touch at certain points only, leaving intervals, 
which, when regular and continuous, are called intercellular passages or 
canals ; when irregular and limited, intercellular spaces or Lacuna. A 
division of cellular tissue is sometimes made into Parenchyma, where the 
cells fit together by plane faces, as in the pith and outer bark, and 
Prosenchyma, where the cells are fusiform, this being confined to the inner 
bark and wood. The mode in which the combination of cells is effected, 
varies under different circumstances; sometimes they are simply approxi- 
mated and fused together, sometimes united by an intercellular matter which, 
in sea weeds, forms a considerable part of the bulk of the plant. 
The external investment of the cell is composed of an unazotized 
primary matter, termed cellulose. This is lined by an originally mucilaginous 
matter containing nitrogen, called Protoplasm, and inside of this is the 
Cytoblastema. A weak solution of iodine applied to the young cell causes 
the protoplasm to turn brown and leave the cellulose. The tissue is further 
modified by the addition of various matters, the most important of which is 
Sclerogen or Lignine applied on the inside, the substance to which wood 
owes its hardness. This consists of 035, 124, O10, and may be dissolved 
by hot nitric acid. In all cell deposits there is a more or less tendency to a 
_ Spiral arrangement. 
Each cell will be found to contain, at one perod of its existence, a small 
body called a nucleus, this often embracing one or two minute dots called 
nucleoli. This nucleus may either lie free in the cell, or be attached by 
threads, or fastened directly to the cell wall. Some recent authorities of 
great weight, however, deny the existence of a primordial nucleus in every 
cell. | 
In addition to the carbon, oxygen, hydrogen, and nitrogen, found 
universally as the constituents of the cell, there are other materials more 
variable in their appearance and amount, as Sulphur, Phosphorus, Potash, 
2 
Vv 
