THE I'.OTANY OF THK FARM. 405 



p-kmt to produce monstrosities was early noticed by cultivators, and care 

 was taken to propagate those individuals which showed abnormal appear- 

 ances. The seeds of such were saved, put into good soil, and no plants 

 e allowed to remain except such as presented the required form. In 

 this manner, certain races of culinary vegetables have been established. 

 If, however, these cultivated plants are allowed to grow wild and scatter 

 their seed in ordinary soil, they will, in the progress of time, revert to 

 the original type or species. Instances such as these show the remark- 

 able effects of cultivation in perpetuating varieties by seed. In regard to 

 th cereal grains wheat, barley, oats, etc. they have been so long culti- 

 vated that we are at a loss to know the original types or species. We 

 have been forced, in the meantime, to call them species, although the}' 

 probably mere cultivated varieties of unknown species, perpetuated 

 ces. * 



It is of great importance to distinguish between mere varieties and true 



species, and to determine the limits of variation of different species. By 



not attending to this, many mere varieties have for the time been described 



nd thus great confusion and incorrectness have arisen both in 



riptions and in arrangements. Another source of fallacy arises from 



hybrids being occasionally reckoned as true species. 



Certain species not identical in origin, have common features of resem- 

 blance, and are associated together under what is called a Genus. A 

 n assemblage of nearly-related species, agreeing with one 

 another, in general structure and appearance, more closely than they 

 accord with other species. Thus, the Scotch rose, the Dog rose, the China 

 and the Sweet-briar, are all different species included in one genus> 

 iiicli is well characterised by its fruit, known as the hep of tli- 

 It may happen that a single species may be reckoned as forming 

 when tin- peculiarities an- as marked as those constituting oi 



\vas only one species of oak, it would l>e sufliei-nt 



itute a genus, as much so EU9 at present when it includes about 200 



It is distinguished ),\- its jic>rn from other allied u. ii.-ra, such as 



: ,'- lia/'-l, and tin- chestnut. Tie in a genius pn 



nil plan, and may l.e >aid to l.e funned after the same pattern. 

 a genus, having -pecial points of resemblan -e, may be 



nU8. 



On looking at genera, it will some of them, rach M 



Mints, have a strong resemblance or family 1 

 y differ remarkably lVm sueh genera a^ !ir> ;uid pines 



3. Certa i\ le grouped so as to 



