
INTRODUCTION TO PLANT HISTOLOGY co we 
CHAPIE vi 
INTRODUCTION TO PLANT HISTOLOGY 
Definition of HISTOLOGY (Gk. histos, web, and logos, a discourse), 
Histology. deals with the minute structure of plants and 
animals; it necessitates the use of a microscope, and is thus 
marked off from Anatomy (Gk. ana, up, temno, to cut), which _ 
is the study of structures as far as they can be made out with 
the naked eye. The examination of any plant, or of any part 
of a plant, under the microscope shows that it consists of a 
cell, or cells, or of structures derived from cells. 
The Protococcus may be taken as a type ol a 
unicellular plant ; it belongs to one of the lowest 
groups of plants, the Algz, and may be obtained by taking 
from a roof-gutter, or trunk of a tree, some of the greenish 
growth present in the water or on the bark of the tree. 
When looked at under the micro- 
scope (Appendix A), Protococci 
are seen to have two forms: one 
without a cell-wall, and moving 
about by means of two delicate 
processes, called cilia (Lat. colawm, 
an eyelash). The absence of a 
cell-wall in this motile Protococcus 
shows that a cell-wall is not an 
essential part of-a cell. | ae | 
The other form of Protococcus — Fy¢, 5.—Moriz Proro- 
is more or less stationary, and cocous. 
sh p, protoplasm with 
OWS: ae chlorophyll granules ; 7, 
1. A cell-wall, consisting of a nucleus; ¢, cilia. 
chemical substance called cellulose. 
2. Protoplasm, in which may be seen a highly differentiated 
Protococcus. 

