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40 ~~ Structural and Physiological Botany. Bia roe 
times, especially in the pileus of certain Fungi, particular 
cell-layers of a ‘tela contexta’ form an apparently regular 
parenchyma, in which however the whole course of de- 
velopment shows that we have here distinct but contiguous 
filaments of cells (z.e. filaments of distinct cells arranged in 
Fic. 63.—Stellate parenchyma from the pith of the rush, ¥uscus conglomer- 
atus ; 2 intercellular space. (Xx 250.} 
rows) ; and a tissue of this kind has therefore been called.a 
pseudo-parenchyma. | 
Other kinds of tissue, distinguished more by their func- | 
tions with respect to the life of the plant than by external 
characteristics, are those termed generating tissue and healing 
tissue. i 
With respect to the production of new cells, even super- 
ficial observation shows that, at least in the higher plants, as 
for example in trees, it does not proceed everywhere uni- 
formly, but is confined to particular spots. ‘To spots of this 
nature the terms ‘ functum vegetationis, vegetative cone, and 
vegetative or formative layer, have been applied, according 
to their degree of development. Instances of ‘puncta 
x 
