24G MANUAL OF AGRICULTUEE. 



altered the functional action of these plants that in their first 

 season's growth they do not develop flowers and seed, but stoi'e 

 up a sufficient supply of nourishment in the hypertrophied parts 

 for the basis of flower and seed growth during the following 

 season. The rape and cauliflower plants are likewise descendants 

 of nearly related stock ; the abnormnl development being seated 

 in the leaf-stalks and leaves of the former, and in the flower-stalks 

 of the latter. Varieties are producible by means of the artificial 

 fertilisation of the seed of one plant through the application of 

 pollen taken from the flower of some other particularly developed 

 plant of the same species. In this way has been porduced the 

 countless' varieties of wheat, barley, oats, and other cultivated 

 plants. Hybrids can also be produced by fertilising the ovules 

 of one species with pollen from the flower of another species. 

 But, in common with the hybrids of the animal kingdom^ these 

 are incapable of reproduction. 



All the grains and grasses of our aimual crops belong to the 

 order Grcrniinece, wdiich is one of the class Endogense ; wherefore, 

 they are all endogenous stemmed, and their seed embryo is mono- 

 cotyledonous. Wheat forms the genus Triticum ; barley, Hor- 

 deum ; oats, Avena ; rye-grass, Lolium ; and so on. 



These genera are respectively subdivided into several species ; 

 these again into innumerable varieties. The bean, pea, and 

 clover plants belong to the order Lcgiiminoscc, of the class Exo- 

 gena3 ; and have therefore exogenous stems, and are dicotyledon- 

 ous. The bean plant constitutes the genus Faba; the pea, Pisum ; 

 and the clover, Trifolium. To the class Exogenpe also belong the 

 turnip, rape, cabbage, kohl-rabi, and wild mustard plants, which 

 with others constitute the order Crucifcrce, with its genera, species, 

 and varieties respectively. 



Chaptek V. — Of Animal Pliysiology. 



There are many striking points of analogy between animal and 

 vegetable physiology. In point of fact, when we look at the 

 elementary organisations in each great natural division, the 

 boundary line betw^een them is difficult to be drawn ; and the 

 forms are numerous, regarding which it is matter of debate as to 

 which great division they properly belong. As we ascend to 

 more highly-developed forms in either, the line of demarcation 

 becomes more readily definable. The highest forms of plant life 

 possess no nervous system, no cavity for the reception and diges- 

 tion of solid Ibod, in other words, no stomach ; and they have 

 no independent power of locomotion ; all of which qualities, on 

 the other hadd, belong to the higher forms of animal life. An- 

 other cardinal distinction is that whilst jDlants can assimilate the 

 elements necessary for building up and maintaining their struc- 

 true from such simple or inorganic compounds as carbonic acid. 



