2 PRELIMINARY. 



spontaneous, as in the plants just mentioned, the denial to 

 them of the same degree of consciousness as is supposed 

 to exist among the infusorial animalcules is a hypothesis 

 unsupported by evidence. 



Mirbel was of opinion that plants cannot be distinugished 

 from animals by any positive character (Elemens de Physio- 

 logic Vegetale, p. 17), but that they form two graduated 

 series, starting from a common point. He more especially 

 objected to the denial of consciousness to plants. " Let us 

 take the Polype," he observes, " a production the least morsel 

 of which produces a new individual. How are we to deter- 

 mine whether^ such beings, which indicate no trace of organs 

 of sensibility, possess the power of perception? We see 

 indeed that they move, catch small insects, and seem to 

 select their food; but certain plants, to all appearance, 

 behave in the same manner. Can we deny the faculty of 

 sensation to the Sensitive or the Dionsea, and yet maintain 

 the presence of this noble attribute among zoophytes ? In 

 this matter we have no other guide than analogy. On the 

 one hand, because zoophytes move in the very same way as 

 animals manifestly provided with nerves and muscles, we 

 assume that their motions have the same origin ; and on the 

 other hand, finding that the few plants which move like 

 sentient beings have nevertheless the greatest resemblance 

 in form, organisation, and development to other plants, which, 

 according to our notions, have no sensibility, we infer that the 

 movements of the last depend upon mere organic contracti- 

 bility, independent of volition and sensation. To this point 

 only goes the intelligence of man in such delicate questions." 

 If in the year 1815, when this passage was written, doubts 

 could thus be raised as to the absence of all traces of per- 

 ception among plants, the argument of Mirbel has become 

 strengthened into conclusiveness now that the habits of plants 

 are better understood. 



Link defines a plant to be an organised body, nourished 

 from without, while animals receive their food from within. 

 But he observes that there are vital actions in which the 

 nutrition of plants and animals is the same, as in the pro- 

 gressive development of the ovule; "at that point plants 



