158 THE POPULAR SCIENCE MONTHLY. 



who shows his notions of accurate statement by asserting that, as I 

 substitute " persistence " for " conservation," I therefore identify Per- 

 sistence of Force with Conservation of Energy, and debits me with the 

 resulting incongruities — one who, in pursuance of this error, confounds 

 a special principle with the general principle it is said to imply, and 

 thereupon describes a wider principle as being included in a narrower 

 (p. 481) — one who speaks of our " inner consciousness" (p. 488), so as- 

 serting, by implication, that we have an outer consciousness — one who 

 talks of an inconceivable conception ; ought surely to be aware how 

 readily lax expressions may be turned into proofs of absurd opinions. 

 And one who, in the space of a few pages, falls into so many solecisms, 

 ought to be vividly conscious that a whole volume thus written would 

 furnish multitudinous statements from which a critic, moved by a spirit 

 like his own, might evolve abundant absurdities ; supplying ample oc- 

 casion for blazoning the tops of pages w^ith insulting words. 



MOKE ABOUT THE GEAPE-YmE PEST. 



By CHARLES V. EILEY, M. A., Ph. D. 



THE number of true (grape-vine) species of Yitis, with the coher- 

 ing petals falling off when the flower opens, and bearing edible 

 fruit, in the territory of the United States, is limited to nine. Of these, 

 four species, viz., Vitis Lahrusca^ov Northern Fox ; Vitis cestivaUs, 

 summer grape; Vitis riparia, river-bank grape; and Yitis vulpina. 

 Southern Fox or Muscadine, are of chief practical consequence as hav- 

 ing yielded our different cultivated varieties. 



I will now proceed to indicate the relative susceptibility to the 

 disease of the cultivated species and varieties. For the sake of con- 

 ciseness, it will be best to indicate this susceptibility by letters and 

 numerals, as follows : 



— Xo perfect leaf-galls found ; or not at all subject to them. 



a — Leaf-galls very rarely found. 



h — Leaf-galls not unfrequently found. 



c — Leaf-galls abundantly found, or very much subject to them. 



— Entirely free from root-lice. 



1 — Having the root-lice in unusually small numbers, but counter- 

 vailing their punctures. 



2 — Koot-lice often numerous ; vines sometimes suffering from their 

 effects. 



3 — Most subject to the root-lice and dying from their attacks 

 whenever the conditions are favorable to their increase. 



European Grape {vinifera), 0, 3. — The very few exceptions, where 

 galls have been found on the leaves of this species, will scarcely invali- 



