320 ON THE MATURATION OF GRAIN 



disease in the stores of 1845, by communication 

 through the unsloughed part of the pendulum, 

 or string attachments, from want of thorough 

 ripening. The same fact may also account for 

 the spreading of the disease through cuts, wounds, 

 and the burrowing holes made in some potatoes 

 by worms and insects. 



I have never seen the attack of an insect 

 followed by gangrene or murrain. The gangrene 

 may infect a leaf attacked by aphides, but as it 

 infects others indiscriminately, that attack can 

 by no means be regarded as its cause. At 

 present there may be seen in all our potatoe 

 crops, leaves infested with the Aphis vastator of 

 Smee, where there is no blight, and contrariwise, 

 blight where there is no Aphis. It starids as a 

 notion, without the support of a single parallel 

 throughout the whole domain of the vegetable 

 creation, that a parasite should poison the food 

 intended to nourish it. Parasites may stunt 

 the growth of plants, malform their organs, by 

 vitiating their juices, or abstract the whole of 

 the nutritive fluid intended to support them, and 

 so cause them to perish, as may be seen in the 

 bean crops, &c. at this moment. 



