The Natural System of Botany. 73 



sent delay. The following remarks are incidentally proper also, 

 for the purpose of explaining many of the terms used in defin- 

 ing the natural orders, without some knowledge of which on 

 the part of the student, we should be frequently obliged to in- 

 terrupt his after progress. Our plan is, as has already been 

 seen, not to pause longer than is unavoidable on the meaning 

 and application of technical words, but rather to trust the ob- 

 servation and memory of the reader to gather the necessary in- 

 formation on such points, as he proceeds. This, so far as our 

 own experience extends, is much better than to continually in- 

 trude upon the senses a collection of compound words, with 

 lengthy explanations, which are almost certain to confound 

 and disgust the mind, and to lead it away from the main sub- 

 ject. We hope in these observations, as well as in the articles 

 on Vegetable Physiology, so to accustom the eye of the student 

 to most of the words which botanists make use of, that when 

 he sees those words collected together, in the form of a diag- 

 nosis, or in the essential characters of a natural order, he will 

 understand them at once, without the trouble of repeated refer- 

 ences to a glossary. This object, to its fullest extent, we can- 

 not pretend to effect, but only so far as concerns the scope of 

 this work. 



Before estimating the degree or the manner in which the ex- 

 ternal organs, such as the leaf, or the flower, are used to deter- 

 mine natural affinities, it may be remarked as a first principle, 

 that for this purpose the value of these organs is proportionate 

 to the certainty with which they severally afford indications of 

 important similarities or differences of general conformation. 

 A single character of an organ may be sometimes a key to all 

 those of the plant or class of plants to which it belongs ; as for 

 instance, a reticulated leaf at once shows that the plant from 

 which it is taken, increases from the outside, has a vascular 

 structure, and a seed composed of more than one cotyledon, 

 because these peculiarities invariably accompany such a leaf. 

 This principle may be made more plain by a reference to the 

 animal kingdom. If a living being is found covered with 

 feathers, we know at once that it has a complete bony skeleton, 

 that its blood is red, it breathes air, its young are produced 

 from eggs, in short, that it possesses all those distinguishing 



