218 ON INSTINCT. 



In supplying the place of reason, it is perpetually assuming its semblance. 

 Let us take an example or two from both the vegetable and the animal world. 



In order that the seeds of plants should produce and perfect their respective 

 kinds, it is necessary that their shoots should rise to the surface of the earth 

 to enjoy the benefit of light and air. Now in whatever direction the eye of a 

 seed, from which germination first radiates, is placed, these shoots ascend 

 equally to the surface, either in curved or straight lines, according as such 

 ascent may be most easily accomplished. Mr. John Hunter sowed a quantity 

 of pease and beans with their eyes placed in different directions, in a tub, 

 which he afterward inverted, so that the bottom was turned uppermost while 

 the mould was prevented from falling out by a fine net. And in order that 

 the under surface might possess a superior stimulus of light and heat to the 

 upper, he placed looking-glasses around the mouth of the tub in such a way 

 that a much stronger light was reflected upon the inverted mould than that of 

 the direct rays of the sun ; while at the same time he covered the bottom of the 

 tub with straw and mats to prevent the mould in this direction from being af- 

 fected by solar influence. Yet the same instinctive law of ascent still prevailed. 

 After waiting a considerable length of time, and perceiving that no shoots had 

 protruded through the lower surface of the mould, he examined the contents 

 of the tub, and found that they had all' equally pressed upwards, and were 

 making their way through the long column of mould above them, towards the 

 reversed bottom of the vessel ; and that where the eyes had been placed 

 downwards, the young shoots had turned round so as to take the same direc- 

 tion. As one experiment leads on to another, he determined to try the effect 

 of placing other seeds of the same kinds in a tub to which a rotatory motion 

 should be given, so that every part of it might be equally and alternately 

 uppermost, and the seeds should have no advantage in one direction over 

 another. Here, as we often behold in other cases, the instinctive principle 

 of accommodation was baffled by a superior power, and the different shoots 

 instead of ever turning round uniformly adhered to a straight line, except 

 where they met with a pebble or any other resistance, when they made a curve 

 to avoid such obstruction, and then resumed a straight line in the direction 

 into which they were thereby thrown, without ever endeavouring to return 

 to the original path. 



Among animals we have various proofs of a like impulse, and we have also 

 proofs of its being occasionally overpowered by a stronger cause. Thus, in 

 cases of eruptive fever, there is an obvious effort of the instinctive principle 

 'to throw the morbific matter towards the surface of the body, where it can do 

 least mischief. And where a deep-seated abscess has formed in the imme- 

 diate neighbourhood of a cavity that cannot be opened into without great 

 danger, as that of the chest or the stomach, the same instinctive principle 

 of preservation leads forward the action in a different direction 1 , though, as in 

 the experiment of the bean-seeds in the inverted tub, with much greater 

 labour and difficulty ; and the abscess at length opens externally; and the 

 remedial process of the formation of new living matter which immediately 

 succeeds, commences under the same mysterious guidance. If, in the course 

 of this common tendency to the surface, an obstructive cause be encountered, 

 of superior force to the instinctive principle itself, the latter, as in the experi- 

 ment of the beans exposed to the action of a rotatory motion, is overpowered, 

 and the result is doubtful, and often fatal. 



But these examples are general : let us advert to a few of a more particular 

 nature. All the different species of birds, in constructing their nests, not 

 only adhere to a peculiar plan, but, wherever they can obtain them, to peculiar 

 kinds of materials : but if these materials be not to be procured, the accom- 

 modating power of the instinctive principle, as in the cases just related, 

 directs them to others, and suggests the best substitutes. Thus the red- 

 breast uniformly prefers oak-leaves as a lining for her nest, wherever she can 

 acquire them; but if these be not to be had, she supplies the want by moss 

 and hair. So where the bird is of small size, and the eggs are naturally nu- 

 merous, the nest is always made proportionally warm, that the nestlings may 



