28 Analogy betweeri Vegetables and Animals 



after both the brain and spinal marrow have been totally 

 destroyed. In the fifth and last place, if the nerves belonging 

 to the right extremity of an animal be divided, as was done 

 in the experiment of Dr. PhiUp, related in his Experimental 

 Inquiry^ while those of the left extremity are allowed to remain 

 entire, and if the corresponding muscles of each extremity be 

 made to contract by the direct application of a stimulant, it 

 will be found that those belonging to the extremity in which 

 the nerves are divided do not lose their contractility sooner 

 than those attached to the extremity in which the nerves are 

 left untouched, and scarcely so soon. Besides, it seems very 

 clear that the involuntary muscles, as in the heart, &c., which 

 are continually moving, have no nerves of motion whatever. 

 They have only nerves of simple sensation ; for these muscles 

 are not stimulated to contract when electricity is applied to 

 the nerves which are distributed to them ; and we know that 

 electric fluid is incapable of acting upon the simply sensitive 

 nerves, while it operates powerfully on the nerves of motion. 

 Such are the proofs that contractility is an inherent power 

 of the muscles, and is independent of the nervous system. 



This being the case, then, it is clear that, although plants 

 may possess a muscular or contractile, they may, nevertheless, 

 be entirely destitute of a nervous, structure; for it is very 

 evident that the existence of the latter is not necessary to that 

 of the former. Since, then, contractility can exist independent 

 of the agency of the nerves, it follows that it may be exercised 

 without consciousness ; for there can be no consciousness 

 apart from a nervous system. Plants, therefore, notwith- 

 standing they are possessed of strong contractile power, may 

 be, nevertheless, perfectly unconscious beings. To prove, 

 indeed, that contractility may be performed without conscious- 

 ness, we have only to take note of what is going on within 

 own persons. The heart and blood-vessels are constantly cir- 

 culating the blood, the bowels are propelling forward the 

 chyle and faeces, and the diaphragm is every moment con- 

 tracting and relaxing. All these functions depend upon con- 

 tractility, and yet they are perfectly imperceptible to the mind. 

 The instinct of plants (for plants possess instinct as well as 

 animals) results from their contractile power. Plants will 

 seek and turn towards the light ; the roots of plants will go 

 in search of proper nourishment, and, if they approach a 

 situation which would be injurious to them, they instantly 

 turn away from it. If a plant be laid on a table, near a 

 sponge filled with water, it will direct its roots towards the 

 sponge. If the sponge be removed to another place, the 

 roots will likewise change their direction in pursuit of it. The 



