280 



THE SUGAR BEET. 



qnently obstructing the respiratory oi'gans of the sickly 

 leaves of plants.^ 



Fig. 77. 



Fiu. 78. 



FijT. 79. 



V\g. 77. — The malady lias penetrated through the radicle, causing a total loss 

 of tiie spongiole. 



Fig. 78. — One of the vessels of the vascular tissue in perfect liealth. 

 Fig. 79. — One the vessels of vascular tissue sutl'ering from disease. 



The fig. 78 represents one of the vessels of the vas- 

 cular tissue in a perfect condition of health. The fig. 

 79 rei^resents the same when attacked, and, as can be 

 seen, the disease seems to have penetrated by degrees 

 the elliptical openings. 



Payen'^ says this brown organic substance resists 



' Our intention had been to make these experiments, but we have not as yet 

 had the leisure. 



^ Mr. Payen and others, in 1851, spoke of methods adopted to prevent the 

 above disease, which are to make use of chemical fertilizers. Fifteen years later 

 lie acknowledges that if these be used in excess they may be the direct cause ot 

 tlie disease. The last hyjiothesis we consider the most rational. 



