BEET, SPINACH, AND CARROT DISEASE. 81 



(325.) The gangrene also attacks the spinach ; and 

 this plant requires attentive consideration, because it 

 appears to be very susceptible of injury. 



(326.) When the vastator attacks this plant, it lives, 

 according to its general habit, upon the under surface of 

 the leaf, and sucks the juices in the usual manner ; parts 

 of the leaf then die or become gangrenous as the result : 

 this, however, is a mere local mischief; but after a time, 

 especially subsequently to rain, the collar of the plant 

 becomes affected, and the entire plant dies at once. 



(327.) The mode in which the disease manifests itself 

 in this vegetable is precisely similar to that in the pota- 

 toe plant when the under-ground stem is affected ; for in 

 this case the upper portion of the root rots, while the root 

 below and the stems above are sometimes not entirely 

 destroyed ; so that the plant is, as it were, cut in two or 

 decapitated. 



(328.) The appearance of the gangrene after rain is 

 interesting, for it shows that the sap, when deprived of its 

 solid parts by this animal, will no longer bear the addition 

 of water ; for in this state of things water so alters the 

 qualities of the sap, that its effect upon the plant is posi- 

 tively poisonous, this vital fluid thus becoming totally unfit 

 to perform the functions of life. 



(329.) The carrot is a useful and important vegetable, 

 which we employ for our nourishment as well as for the 

 food of cattle. It however is attacked by the vastator, and 

 rots under its influence. (Plate vii., fig. 1.) 



(330.) The insect lives in the first instance upon the 

 larger leaves, which it destroys locally in the different 

 parts attacked. After a time the central portion of the top 

 of the carrot begins to rot ; this rot extends downwards 



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