64 ASSOCIATION OF ORGANISMS—THE WEB OF LIFE 
of natural objects upon which much of the future happiness of our 
embryo citizens will depend. If properly taught as a connected 
whole, and not as a string of isolated facts (to be “learnt ”), this 
subject ought to fare better than physiography and general ele- 
mentary science, which, though designed with the laudable inten- 
tion of giving a broad foundation in non-biological science, are 
now somewhat discredited. 
The relations which bind together the innumerable plants and 
animals now living on the globe are so numerous, and often so 
complex, that from this point of view the world has been com- 
pared to a spider’s-web of elaborate texture, in which all the 
threads are directly or indirectly connected, so that when one is 
touched the entire structure is thrown into vibration. 
It is not within the scope of this work to deal with the com- 
plex relations which link together the members of the vegetable 
kingdom, and students who desire information of this kind are 
referred to the English edition of Schimper’s Plant Geography, 
to Kerner von Marilaun’s altogether admirable book Zhe Natural 
History of Plants, and also to Scott Elliot's Mature Studzes, which 
gives an excellent account of the leading facts and principles in 
small compass. But it may be well to attempt here a brief 
description of the salient features which mark the relations exist- 
ing between plants and animals. This is much more fully dealt 
with by the authors just mentioned. 
PLANTS AND ANIMALS 
It may not be superfluous to remark here that the vegetable 
world is divided into the following great groups, beginning with 
the highest:—1. Seep PrLants (Spermaphyta), including most of 
the large and obvious forms, such as ordinary forest-trees and 
the inhabitants of our flower-gardens. 2. FERN-LIKE PLANTS 
(Pteridophyta), comprising not only ferns, but also horse-tails, 
club-mosses, &c. 3. Mosses anp Liverworts (Bryophyta). 
4. Lower Prants (Thallophyta), in which the body is not divided 
into stem, root, and leaf, or such a division is only incipient. 
Multitudes of Thallophytes are minute or microscopic, and in any 
case they may broadly be assigned to one of three sub-groups: 
(2) Alge, embracing brown, green, and red sea-weeds (with a 
smaller number of freshwater weeds), with a host of smaller 
