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 7^he Natural 

 History of Plants, and also to Scott Elliot's Nature Studies, 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: i. SEED PLANTS (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 AND LIVERWORTS (Bryophyta). 

 4. LOWER PLANTS (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: 

 (a) Algce, embracing brown, green, and red sea -weeds (with a 

 smaller number of freshwater weeds), with a host of smaller 



