Rev. P.Keith on the Susceptibilities of Living Structures. 253 



tion? — If a dead frog has been made to leap by means of the 

 agency of this power, and a dead man to shake his fist in the 

 face of the experimenter, well might we ascribe the shrinking 

 of the Mimosa, the collapsing o{ Uioncea, and the elastic spring 

 oi Stylidium, to a similar cause. 



Further, the advocates of the doctrine of vegetable sensa- 

 tion have claims of a still higher order, which they advance in 

 addition to those already stated. They contend that they 

 find in vegetables movements that indicate not only sensa- 

 tion but also instinct*. — 1st. When a seed is deposited in 

 the soil, in whatever position, the radicle as it elongates will 

 descend in a perpendicular direction and fix itselt in the earth, 

 and the plumelet issuing from the opposite extremity of the 

 seed will assume a vertical position, and ascend into the air. 

 This is the natural order of the development of the parts of 

 the seminal germ, and no human art has ever been able to 

 make them assume contrary directions, or to convert the one 

 into the other. — 2ndly. In the spiral ascent of the twining 

 stem, the winding is never effected at random, but always in a 

 determinate manner in the same species. Some stems wind 

 round their prop in a direction from left to right, or according 

 to the apparent motion of the sun, and never otherwise, as in 

 the cases of the honeysuckle and hop. Others wind round in a 

 direction from right to left, or contrary to the apparent mo- 

 tion of the sun, and never otherwise, as in the case of Convol- 

 vulus Sepitim and the scarlet kidney-bean. — 3rdly. The tendrils 

 of many plants requiring support, are not satisfied to embrace 

 their prop by taking merely a single turn around it, but are 

 found to multiply their circumvolutions till they have got a 

 hold that is inseparable ; and there are cases in which, after 

 taking a certain number of circumvolutions in one direction, 

 they are found to turn suddenly round, and to take as many 

 more in a contrary direction. 



What less than instinct, it has been said, could direct them 

 in these unerring and unalterable movements? — The fact is 

 indeed inexplicable, and yet the admission of instinct is but 

 a confession of our ignorance of the cause. Neither do we 

 think that the term is rightly applied to express the growth 

 of any organ or fabric. The legitimate use of it seems lather 

 to be confined to the expressing of the act of an individual 

 being regarded as sentient. We might as well say that the 

 upward growth of the teeth of the lower jaw, and the down- 

 ward growth of the teeth of the upper jaw, and the twisted 

 and spiral growth of the horns of the ram, are the result of 

 an instinct born with, and inherent in these organs. But 



* Darwin's Zoon. vol, i. Sect. 16. 



findinjr 



