144 HOW CROPS GROW. 



fluences the relative development of the organs of a plant. 

 In a dry season, plants remain stunted, are rougher on the 

 surface, have more and harsher hairs and prickles, if these 

 belong to them at all, and develope fruit earlier than 

 otherwise. In moist weather, and under the influence of 

 rich manures, plants are more succulent, and the stems and 

 foliage, or vegetative parts, grow at the expense of the re- 

 productive organs. Again, different varieties of the same 

 plant, which are often quite unlike in their style of devel- 

 opment, are of necessity classed together in our table, and 

 under the same head are also brought together plants 

 gathered at different stages of growth. 



In order that the wheat plant, for example, should always 

 have the same percentage of ash, it would be necessary 

 that it should always attain the same relative development 

 in each individual part. It must, then, always grow under 

 the same conditions of temperature, light, moisture, and 

 soil This is, however, as good as impossible, and if we 

 admit the wheat plant to vary in form within certain lim- 

 its without losing its proper characteristics, we must ad- 

 mit corresponding variations in composition. 



The difference between the Tuscan wheat, which is cul- 

 tivated exclusively for its straw, of which the Leghorn 

 hats are made, and the " pedigree wheat " of Mr. Hallett, 

 (Journal Roy. Ag. Soc. of Etig.^ Vol. 22, p. 374,) is in some 

 respects as great as between two entirely different plants. 

 The hat wheat has a short, loose, bearded ear, containing 

 not more than a dozen small kernels, while the pedigree 

 wheat has shown beardless ears of 8| inches in length, 

 closely packed with large kernels to the number of 120 ! 



Now, the hat wheat, if cultivated and propagated in the 

 same careful manner as has been done with the pedigree 

 wheat, would, no doubt, in time become as prolific of grain 

 as the latter, while the pedigree wheat might perhaps with 

 greater ease be made more valuable for its straw than its 

 grain. 



