226 THE POPULAR SCIENCE MONTHLY. 



spontaneous movements), and a low form of sensation, which he 

 supposes might be accompanied by a degree of consciousness 

 " and as sensation does exist in animals independently of those 

 eminent attributes with which it is combined in our natures as 

 rational agents, may we not reasonably infer that vegetables have 

 likewise their share of sensitive power, and consequently the 

 means of enjoying their existence ? " Hence, as vegetables are ne- 

 cessarily so different from animals in their mode of existence, it 

 is very evident that we can not form any idea how they feel under 

 any circumstances ; but we are not on this account to conclude 

 that they are destitute of every kind of sensation. "As they 

 possess life, irritability, and motion, spontaneously directing their 

 organs to what is natural and beneficial to them, and flourishing 

 according to their success in satisfying their wants, may not the 

 exercise of their vital functions be attended with some degree of 

 sensation, however low, and some consequent share of happi- 

 ness ? ( Vide Smith's Introduction to Botany.) " 



Biological literature even in recent years abounds in expres- 

 sions concerning phenomena of plant life corresponding to the 

 sensorial action of animals. These conceptions were fostered to 

 some degree by Charles Darwin's Power of Movement in Plants 

 and other works, in which the actions of plants are described in 

 terms strictly applicable to the sensorial reactions of animals only. 

 Thus he says of the irritability of the tips of roots, " It is hardly 

 an exaggeration to say that the tips of the roots affected and hav- 

 ing the power of directing movement in the adjoining parts act 

 like the brain of the lower animals." This phraseology was, no 

 doubt, intended to be suggestive rather than definitive, but to it 

 may be traced many current erroneous impressions. " Instinct," 

 " intelligence," " nervous action," and a score of similar terms are 

 used indiscriminately to designate actions of plants far removed 

 in character from those denoted by the original meaning of such 

 expressions. A partial justification of this misapplication of 

 terms is found in the lack of systematically arranged information 

 concerning the form of sensibility exhibited by plants. With an 

 extensive nomenclature dealing with the great mass of detail of 

 the neuro-muscular action of animals at command, the apparent 

 similarity between the irritation reactions of plants and the 

 sensorial reactions of animals has been held to be real, in a 

 manner strongly suggestive of the anecdote of the German 

 peasant who, seeing a moving locomotive for the first time, ex- 

 claimed, " There's a horse inside of it, or how could it run ? " 



The conception of the relative character of these two great 

 groups of reactions may be attained by outlining the conditions 

 which have led to the development of each rather than by an 

 accentuation of external similarities. 



