83 DOG'S-TOOTH GRASS. 



We admit that these data leave much to be desired from 

 a chemical point of view. We may well ask, for example, how 

 the illustrious philosopher ascertained the presence of sal- 

 ammoniac in nightshade ? But it is not fair to criticise the 

 science of the past, by judging it through the deceitful prism 

 of the science of to-day. We must adopt the methods of our 

 predecessors, when discussing natural productions from all the 

 view-points of their applications. 



DOG'S-TOOTH GRASS. 



In clearing an uncultivated field we uproot a great number 

 of herbaceous plants of different families ; but those of the 

 Graminece, or Grasses, invariably predominate. They are .the 

 trailing roots, or rhizomes, of certain species which have been 

 included under the general denomination of Dog's-tooth. 

 These tenacious and vigorous roots, so wholesome in various 

 maladies, so injurious to cultivation, are, whatever certain 

 botanists may say, far from tracing their origin in all cases 

 to the Triticum repens (couch-grass) and Panicum dactylon 

 those terrible enemies of the corn-field, which, once estab- 

 lished in the soil, are with difficulty extirpated, and prove 

 very injurious to the "golden crops." Nearly every grass 

 which puts forth rhizomes will furnish the Dogs-tooth. We may 

 cite, for instance, several species of Festuca (as Festuca rubra 

 and Festuca pinnatd), or fescue grass ; at least two kinds of 

 meadow grass (Poa compressa and Poa pratensis), a species of 

 wild-oats (Avena elatior\ to say nothing of the weeds Arundo 

 fihragmites and Arundo epigeios. The long rhizomes of these 



