238 



OiS INSTINCT. 



A strawberry ofiset planted in a patch of sand will send forth almost 

 the whole of its runners in the direction in which the proper soil lies 

 nearest, and few, and sometimes none, in the line in which it lies most 

 remote. 



" When a tree which requires much moisture (says Mr. Knight,) has 

 sprung up or been planted in a dry soil, in the vicinity of water, it has 

 been observed that much the larger portion of its roots has been directed - 

 towards the water ; and that when a tree of a different species, and 

 which requires a dry soil, has been placed in a similar situation, it has ap- 

 peared in the direction given to its roots, to have avoided the water and 

 moist soil."* 



" When a tree (remarks Dr. Smith) happens to grow from seed on a 

 wall, (and he particularly alludes to an ash in which the fact actually ojc- 

 curred,) it has been observed, on arriving at a certain size, to stop for a 

 while and send down a root to the ground. As soon as this root was 

 established in the soil, the tree continued increasing to a large magni- 

 tude, "t 



The best means, perhaps, that a plant can possess of resisting tbe ef- 

 fects of drought, is a tuberous or bulbous root. The grass called phleum 

 pratense^ or common catstaiU when growing in pastures that are uniformly 

 moist, has a fibrous root, for it is locally supplied with a sufficiency of 

 water ; but in dry situations, or such as are only occasionally wet, its root 

 acquires a bulbous form, and thus instinctively accommodates the plant 

 with a natural reservoir. And there are various other grasses, as the 

 alopecurus geniculatus^ or geniculate foxtail, that exhibit the same curious 

 adaptation. I 



There are some philosophers and physiologists who have endeavoured to 

 ascribe the whole of these very extraordinary phaenoittenato the mechani- 

 cal powers of gravitation and centrifugal force , among whom 1 may es- 

 pecially mention Mr. Knight, who has attempted it in the very ingenious 

 paper to which I have just alluded. There are others who ascribe them 

 to the operation of an intelligent principle, among whom, more especially, 

 as I have already observed, is Dr. Darwin. Of these two causes the in- j 

 stances just submitted to you, and thousands more might be added to | 

 them, sufficiently prove that the first is inadequate, and that the second | 

 does not always exist ; at least that the phaenomena are often found in or- \ 

 ganized forms in which, to a certainty, the precise organs do not exist, 

 which are the only known seats of intelligence and sensation in the visible 

 world. They are hence to be resolved into another cause, equally remote 

 from either, more complex in its operations than that of gravity, but less 

 so perhaps than those of intelligence and feehng ; embracing a distinct'^ 

 family of well-defined and cognate actions, always aiming at the same 

 common end, the perfection, preservation, or reproduction of the system, 

 in which they exist ; and constituting what we should denominate instinct, 

 the general property of the living principle, or the law of organized life in 

 a state of action. 



But the subject is too important to be closed here. It remains yet to 

 point out the difference between instinct and sensation or feeling, as well 



of instincts in insects, see Swedish Amcenitates Academicse, vol. iii. art. 45. Noxa Insec- 

 torum, by M. A. Boechner 1752 ; and compare with these the younger Ruber's Recherche? 

 sur les Moeurs des Fourrais Indigenes. 



♦ Phil. Trans. 1811. p. 210. t Introd. to Botany, p. tl4. 



I See Smith, Introd. to Bot. p. IIS. and p. 41. 



