138 GRAMMAR OF ENTOMOLOGY. 



exclusive part. These conclusions lead to the 

 probability of a third, that brain and nerve are 

 but different states of the same system of organs. 



515. The vitality, therefore, concentrated in a 

 brain, may be diffused through the nerves when 

 there is no brain, and each mass of nerves maybe 

 the seat of that small power of mind which insects 

 possess. 



516. The nervous cord extending, as described, 

 from one end of the insect to the other, is com- 

 pared to, and has been called the, spinal marrow ; 

 its first knot, or incrassated portion, the brain; 

 the following knots, ganglions : this nomenclature 

 appears arbitrary, as we have seen that no parti- 

 cular portion exercises exclusively the functions 

 of a brain. 



517. It appears better to consider each of the 

 little knots a separate and independent centre 

 of volition, as it undoubtedly possesses the cha- 

 racters of such, giving out its various nerves in 

 the same manner as the human brain. 



518. All anatomical operations succeed best 

 with the larvae of insects, because the constant and 

 obvious division of the body of larvae into thirteen 

 segments, afford us more ready means of describing 

 the result of observation ; whereas, in perfect in- 

 sects, several segments are liable to become united, 

 and the exact boundaries of each are thus rendered 

 subjects of doubt. 



519. It must also be observed, that the internal 



