: ree’ * 
) 
Pr, ) . . ‘ . ; - ty he 
vegetationis’ occur in the apices of buds ; of formative layers 
between the wood and the bark of [exogenous] trees. Both 
owe their special character to the formation of new cells or 
arate The Cell as a Member of a Group. 41 
organs by means of a special tissue to which the names 
Fic. 64.—Transverse section through the collenchyma of the sowthistle 
Sonchus asper: a epidermis : c collenchymatous cells. (x 670.) 
formative or generating tissue and meristem have been given. 
In contrast to this, a tissue in which the cells are not as a 
rule capable of dividing, is called a permanent tissue; and 
the separate cells which no longer serve for the formation 
of new cells, permanent cells. 
The generating tissue of the ‘punctum vegetationis’ of 
flowering plants is parenchymatous, and is called primary 
parenchyma or primary meristem, because every kind of cell 
and every part of the plant may or actually does develope, 
directly or indirectly, from it. Independently of growth by the, 
actual increase in size of the individual cells, the apical 
/ 
