338 DEFINITION OF SPECIES. 



defined, or what is termed Glossology (yAaWa, a tongue or language, 

 and Ao'yo?, a discourse), and Termonology (rlytuv, 'oo?, a termination). 

 The meaning of the terms in this descriptive language must not depend 

 on fancied resemblances, but must have a precise definition, and be 

 constant. In acquiring a knowledge of the conventional terms, or of 

 the vocabulary of the science, the student at the same time fixes in 

 his mind the perceptions and notions which these terms convey, and 

 thus, in reality, becomes acquainted with important elementary facts. 

 2. A Plan of the system, or the principles on which the divisions and 

 subdivisions of the system are made, Diataxis (d/arai/?, orderly arrange- 

 ment), or what is properly called Taxonomy (rdfa, order, and j/o^o?, 

 law). There have been two great plans proposed in Botany, one 

 denominated artificial, the other natural. The first is founded on 

 characters taken from certain parts of plants only, without reference 

 to others; while the second takes into account all the parts of plants, 

 and involves the idea of affinity in essential organs. 3. There must be 

 also the means of detecting the position of a plant in a system by short 

 diagnostic marks. In doing so, a few essential characters are selected 

 in accordance with natural affinities. The division into genera is a 

 most valuable help in determining plants. Linnaeus did great service 

 to science by his generic divisions, and by adopting a binomial (bis, 

 twice, and nomen, a name) system of nomenclature, in which the genus 

 and species are included in the name of the plant. 



705. Species. No classification can be made unless the meaning of the 

 term species is defined. By species, then, are meant so many individuals 

 as are presumed to have been formed at the creation of the world, and 

 to have been perpetuated ever since. A species embraces individuals 

 which resemble each other more closely than they do any other plant, 

 so that they are considered as originating from a common parent; and 

 their seeds produce similar individuals. There may be differences in 

 size, colour, and other unimportant respects; and thus varieties may 

 exist, exhibiting minor differences, which are not, however, incom- 

 patible with a common origin. Varieties owe their origin to soil, expo- 

 sure, and other causes, and have a constant tendency to return to the 

 original type. They are rarely propagated by seed, but can be per- 

 petuated by cuttings and grafts. By cultivation, permanent varieties 

 or races have been produced, the seeds of which give rise to individuals 

 varying much from the original specific type. Such races are kept up 

 entirely by the art of the gardener, and may be illustrated in the case 

 of the Cereal grains, and of culinary vegetables, such as Cabbages, 

 Cauliflower, Brocoli, Turnips, Radishes, Peas. It is only after a 

 series of years that these permanent varieties have been established, 

 and there is still a tendency in their seeds, when sown in poor soil and 

 neglected, to produce the original wild form. Permanent varieties in 

 the animal kingdom may be illustrated by the different races of man- 



