831 



of these important parts of the plant are essential to the perfection 

 of the tuber, which they were, by nature, destined to ventilate and 

 purify." 



" July 27, 1846. " 



Mr. Smee and his Aphis vastator. 



In a late number of the ' Phytologist ' we noticed Mr. Smee's work 

 on the potato-disease as a pleasant and well-timed jeu d'esprit, cal- 

 culated to arrest, in some measure, the torrent of hypotheses with 

 which the press was at that time teeming on the same subject. As a 

 jeu d'esprit, and written with a benevolent intention, it claimed our 

 respect and admiration ; but we think the author has subsequently 

 taken up the subject a little too strongly, and we beg to caution him 

 against such advertisements as the following, extracted from Satur- 

 day's ' Sun,' lest he unexpectedly find the public laughing at him 

 instead of with him ; an unpleasant difference. 



" IMPORTANT EXPERIMENTUM CRUCIS, or direct proof 



OF THE DESTRUCTION OF THE POTATO PLANT BY THE APHIS 

 VASTATOR. 



" Sir, — In my treatise on the potato plant, I have shown that, an- 

 tecedently to all other changes, a certain insect is to be found on the 

 leaf, which sucks the juices of the plant and causes it to die, locally, 

 at the part affected, or generally through its entire system. 



" By tracing the insect to numerous other plants it was found to 

 produce similar eflFects — the turnip rotted in the bulb, the carrot in the 

 root, and even the indestructible groundsel equally suflFered from its 

 attacks. In the damaged plants anatomy demonstrates imperfect tis- 

 sue — chemistry, a deficiency of the solid materials, and natural history 

 indicates the source of the mischief by pointing to the creature which 

 abstracts that which should form the fibre and starch of the plant. 



" To those who prefer experiment to observation I have now to 

 announce that at length the direct proof of the capability of the Aphis 

 vastator to destroy the potato plant has been obtained ; an experi- 

 ment which has already been performed with the same result upon 

 tulips, crocuses, and other plants. 



" Several Russian tubers, apparently sound and well filled with 



