298 HOW CROPS GROW. 



degree departed from the original specific type. Thus 

 nature puts the same limit to variation within a species 

 that she has established against the mixing of species. 



Darwin s Hypothesis, which is now accepted by many 

 naturalists, is to the effect that species, as above defined, 

 do not exist, but that new kinds (so-called species) of ani 

 mals and plants may arise by variation, and that all exist 

 ing animals and plants may have developed by a process 

 of &quot; natural selection &quot; from one original type. Our ob 

 ject here is not to discuss this intricate question, but sim 

 ply to put the reader in possession of the meaning attach, 

 ed to the terms currently employed in science termF 

 which must long continue in use and which are necessarily 

 found in these pages.* 



Genus, (plural Genera.) In the language of anti-Dar- 

 winianism, any set of oaks that are capable of reproducing 

 their kind by seed, but cannot mix their seed with other 

 oaks, constitute a species. Thus, the white oak is one 

 species, the red oak is another, the water oak is a third, 

 the live oak a fourth, and so on. All the oaks, white, red, 

 etc., taken together, form a group which has a series of 

 characters in common that distinguishes them from all other 

 trees and plants. Such a group of species is called a genus. 



Families OF Orders, in botanical language, are groups 

 of genera that agree in certain particulars. Thus the sev 

 eral plants well-known as mallows, hollyhock, okra, and 

 cotton, are representatives of as many different genera. 

 They all agree in a number of points, especially as regards 

 the structure of their fruit. They are accordingly group 

 ed together into a natural family or order, which differs 

 from all others. 



Classes, Series, and Classification, Classes are groups 



* For a masterly statement of the facts and evidence honrinu: on these points, 

 wliirli arc of the &amp;lt;jv;ilc st importance to the ;i^rieiilturist, see Darwin s works 

 &quot;On the OriLMn of Species/ and &quot;On the Variation of Animals and Plant* 

 mler Domestication.&quot; 



