50 THE GKASSES 



gate of individuals, descending from one another and from 

 common ancestors, and those which resemble them as strongly 

 as they resemble one another, should be called Species. 



Groups of similar or related species are called Genera.- 



Groups of genera similarly related as the above constitute 

 Families. 



The highest generalizations are denominated Classes and 

 Divisions. 



All these divisions have received special denominations, 

 and the identity of an individual is recognized by the ex- 

 pression of the name of its generic and specific name, e. g. 

 viola odorata, scented violet ; liliaum oandidum, white lily. 



All plants, from the minute to the gigantic, simplest or 

 wonderfully complex, whether aquatic, terrestrial orparisitio, 

 in considering their method of propagation, can be grouped 

 into two series : 



Series I. Phsenogamous, or flowering plants, which pro- 

 duce flowers and seeds, the latter containing a ready-formed 

 embryo. 



Series II. Cryptogamous, or flowerless plants, whose 

 organs of reproduction are not flowers, but some more or 

 less analagous apparatus, and which are propagated by 

 spores or specialized cells. , 



Omitting the cryptogamous series, which has no repre- 

 sentatives amongst our meadow and forage plants, except as 

 occasional intruders and fearful enemies to their life and 

 development, in which respect they will be hereafter shortly 

 mentioned, and scrutinizing the structure of the Phaenoga- 

 mous series, we shall find that their growth or increase takes 

 place either by an annual addition upon the periphery — 

 exogens, "outside growers" — or the newly formed woody 

 matter is intermingled with the old, or deposited towards 

 the center, which becomes more and more occupied with 

 the woody threads as the stem grows older, and the increase 

 in diameter takes place by gradual distension of the whole ; 

 such, plants are called endogens, or " inside growers." 



