DESCRIPTION OF PLATES. 179 
SECTIONS OF VEGETABLE TisssuES (PLATE IX. Fic. 1; 
Puate X. Fies. 1 anp 2; anp Puare XI. Fis. 1 
AND 2). 
In the epidermis of plants, we have had an 
example of the methods in which flattened cells 
are joined side by side to form an investing 
membrane for the higher plants. We have now 
to glance hastily at the imterior structure of 
these, and we shall find that here also we have 
uniformity in plan and diversity in execution. 
With cells of various forms and dimensions as 
the architectural units, we have formed a va- 
riety of vegetable tissues which serve various 
purposes in the economy of the plants of which 
they are a part. 
In a work of this kind, anything more than 
the merest outline with regard to this subject 
would be out of place, and the reader whose cu- 
riosity is aroused by an inspection of the photo- 
micrographs (Plates IX., X., and XI.) in the 
present volume, can easily obtain detailed in- 
formation from standard botanical text-books. 
A very beautiful example of cell-masonry is 
seen in Plate IX. Fig. 1, which is from a trans- 
verse section through the petiole of Calla. Here 
the cells of the pith are built up into partitions 
enclosing cavities, and we have thus formed a 
structure having considerable strength, with a 
comparatively small expenditure of material. In- 
stead of partition walls, we sometimes have, in 
endogenous stems, cavities, the walls of which are 
