504 PSYCHOLOGICAL PHYSIOLOGY. 



EIGHTH CHAPTER. 



OF THEIR SELF-PRESERVATION. 



287. 



THE means which insects make use of for self-preservation are of 

 two kinds, as they refer to their mode of procuring food and to their 

 means of defence against their enemies. They both evince in so many 

 instances an amount of sagacity, that we feel astonished at the apparent 

 high degree of reflection and consideration announced by it ; indeed 

 they Avould absolutely convince us of a freer activity of the mind, did 

 not the same phenomena of necessity and a want of freedom exhibit 

 itself in as far as that every individual repeats the same processes in 

 the same manner and in perfect concordance even to their minutest 

 details, without having learnt it from its predecessors. 



I. MEANS OF DEFENCE. 

 288. 



The means insects have received from nature for their defence may 

 also be viewed under two aspects, namely, first, as a passive means 

 derived from the form and structure of their bodies, and, secondly, as 

 an active means of defence derived from the free exertion of strength on 

 the part of the insect. 



Passive means of defence are derived chiefly from the form and 

 colour of the body, by their giving insects such a resemblance to the 

 objects in or upon which they dwell, that upon superficial observation 

 it is not easy to distinguish them from it. To give examples of this, 

 we might remind our readers of the similarity of colour of many beetles 

 to the ground upon which they are found. This is strongly exemplified 

 in the large family of Curculios, in which the majority of the species 

 of the genera Thylacitcs, Sitona, Truchyphlceus, Chonis, &c. are of an 

 earthy grey or yellowish, like the sand or loamy soil where they creep. 

 Tliylaciles incaniis is of a brownish yellow, like that of the colour of 

 the earth of the woods covered with fallen pine leaves. Thylaciles 



