CHAPTER I. 
THE TISSUES OF PLANTS. 
33. Some plant-cells live alone, and are not connected 
with any others; some which are at first separate afterward 
unite into a cell-colony. In most cases, however, the cells 
are united to each other from the beginning of their exist- 
ence into what are called tissues. 
34. As understood in this book a plant-tissue is an assem- 
blage of similar cells which have been united with each 
other from their beginning. The cells in a tissue may be 
arranged in rows, surfaces, or masses: in the first the 
growth has been by the fission of cells in one plane only, 
in the second from fission in two planes, and in the third 
from fission in three planes. 
35. In the lower plants the cells are all alike, or so nearly 
so that they constitute but one kind of tissue. As we 
ascend from these simple forms the cells begin to show 
differences, some being especially developed for one pur- 
pose, and some for another; and these differences become 
more numerous and more sharply marked as we approach 
the higher plants. This at last gives us many kinds of 
tissues, which may be distinguished from each other by 
characters of greater or less importance. However, they 
may all be brought within seven general kinds, each kind 
showing many varieties. 
36. Soft Tissue (Parenchyma).—This is the most abun- 
dant tissue in the vegetable kingdom; it is at once the 
