62 SIXTH ANNUAL REPORT 



charged with Phylloxera in all stages. The result has verified my 

 anticipation: the infected vines became sickly, and passed through 

 the conditions already described, which indicate the disease. After a 

 brief period of rest, late in the fall, I brought all the vines in a warm 

 room. The infected vines are now dead, and an examination showed 

 their roots rotted and wasted; the non infected vines are living and 

 growing finely. To the same effect is the experience of Mr. Malcolm 

 Dunn, a gardener of Powerscourt, Ireland, who, finding that the vines 

 in his grapery were suffering from Phylloxera, uprooted them and 

 carefully cleansed the roots and freed them of the insect. After 

 replanting in new earth he had the pleasure of seeing the vines regain 

 their vigor. "I am the last to deny that meteorological conditions 

 accelerate or retard the multiplication of plant-lice, as they do of so 

 many other insects; but I see no reason for presupposing a diseased 

 condition of the plant first attacked by them, when, as every ento- 

 mologist knows, they can flourish only on living vegetation, which 

 they forsake when its life has been sapped. Conditions may be favor- 

 able to the increase of the plant-lice on our hops, of cotton-worms, of 

 the Army- worm, and of a thousand well-known insect pests ; yet no one 

 doubts that if, by increased effort, we, in some way or other, prevent or 

 destroy these insects, we effectually overcome the (to us) unfavorable 

 conditions, and our plants thrive. 



"Whenever abundant enough to attract attention, these plant-lice 

 have already brought the infested plants into a state of disease, and it 

 is this fact which blinds so many persons, and makes them so ready to 

 believe that it was the diseased condition which attracted, or as some 

 more ignorantly put it, produced the lice."* That conditions of soil 

 and atmosphere may favor or retard the multiplication of Phylloxera, 

 will not, therefore, be doubted by any one ; but that an insect which 

 thrives most on the more vital and growing parts of the plant shows,, 

 in the winged state, a preference for a weak vine over a healthy one,. 

 is in itself highly improbable ; while the supposition that the wingless 

 form, in its spread from vine to vine, shows any such preference, is 

 entirely groundless. 



Again, another set of writers maintain that the insect is not 

 American, and that it has always existed in France, and is autoch- 

 thonous wherever found. The facts already presented will, I hope, 

 sufficiently refute this theory. We might naturally infer, a prioriy 

 that the insect was imported into Europe; for it requires a great 

 stretch of imagination to suppose that it had remained dormant and 

 unnoticed for centuries, to suddenly appear in several different and 



♦5th Rep., p. C8. 



