332 THE VEGETABLE WORLD. 
the Pinacew and Cicadeacee this order differs in the greater per- 
fection of its reproductive organs, while the ovules are covered 
with a pericarpal integument, opening at the summit.” 
n the osperms, which connect the lower with higher 
forms of organisation, the transition is very distinctly marked. 
In Cycads the stem is simple and cylindrical, the departure from 
its terminal mode of development being exceptional and acci- 
dental, while the Conifers exhibit a constant tendency to a rapid 
evolution of leaf-buds in every axil. An increasing value in their 
products is also observable. The Cycads, for instance, yield a 
mucilaginous juice, mixed with starch, from which common 
articles of food are prepared. At the Cape of Good Hope the 
fruit of the various species of Encephalartos are called “ Catire 
bread,” and a kind of arrowroot is prepared in Mexico from the 
seeds of Dion edule. In Japan a sago is procured from the cel- 
lular substance occupying the stem of Cycas revoluta, and also 
from Cycas cireinalis in the Moluccas. Other species are also 
utilised in the countries of which they are natives. The Pines 
and Fir-trees are chiefly valuable for their timber, and the Yews 
and their allies are valuable for their resinous products, and also 
for timber, which is unsurpassed for elasticity and durability ; and 
in Amboyna the seeds of Gnetum Gnemon are eaten F . 
boiled, or fried, and the green leaves are a favourite vegetable 
eaten and cooked as spinach. 
Cis ee 
Crass VII.—ExoceEns. 
The Dicotyledons of Jussieu, and the Exogens of more recent 2 
botanists, include the more highly organised plants, which 
Moreover endowed with proportionate vitality, for “ while a cen 
tury or two terminates the existence of most endogenous ere 
some existing Exogens were monarchs of the forests at the be: & 
ginning of the Christian era.” As already eX] Jained, air 
add their new wood to the outside between the bark and wood ne 
last year’s growth. ; Peal 
The class of Exogens numbers over 66,000. Their germinate! 
is exerhizal, the embryo with two or more cotyledonous 1*°" 
having a network of veins ; the trunk formed of woody bundles 
