158 OUR FARM CROPS. 



surface before ploughing ; or shallow breast - ploughing 

 about two inches deep, by destroying the roots of the 

 grasses, will starve the wireworms. The slug-like larvse 

 of a beetle (Crioceris melanopa and G. merdigerd) appear 

 to attack the leaves of the oats just about the time they 

 are coming into ear. The insect itself is of a dark colour 

 green and black with a shining coat, and antennae twice 

 as long as the thorax. The caterpillars of the wainscot- 

 moth (Leucania obsoletd), also have been observed to 

 attack the leaves, but without doing them otherwise much 

 injury. 



Notwithstanding the inferiority of the oat in economic 

 importance to the two cereals already discussed, its Che- 

 mistry has been the object of attention of several eminent 

 chemists, whose labours have made us perfectly acquainted 

 with its composition in well-nigh every stage of its growth. 

 On the Continent, Boussingault, Krocker, and Hermb- 

 stadt have investigated its composition; while, at home, 

 the elaborate investigations of Norton, Horsford, Way, 

 and Voelcker, have placed us in possession of a full know- 

 ledge of its various constituents. 



The relative proportion of grain to straw has been 

 estimated by Schwerz at 37 of the former to 63 of the 

 latter. This estimate, made on the Continent, coincides 

 pretty well with the results obtained by Mr. Norton in 

 Scotland, 1 who gives, as the average of ten samples, the 

 relative proportions as follows : grain, 6 ; straw, 9 ; 

 chaff, 1. These different parts of the plant (Hopetoun 

 Oat) were separately examined by him, and found to con- 

 tain very different proportions of organic as well as inor- 

 ganic matter. In the grain he found 2 '14 per cent., in 

 the straw 5'8 per cent., and in the chaff 16'53 per cent, 

 of mineral matter (ash), existing in the following pro- 

 portions : 



1 High. Soc. Trans., 1846, p. 321. 



