112 RAMBLES OF A NATURALIST. 



see by the microscope*, imparts to it its brilliant 

 colours, lift up layer after layer, and when the 

 organs are gradually exposed to view, I promise 

 you that all your labours will be more than repaid. 



You must begin with the nervous system, which 

 is an apparatus of such predominating influence that 

 it has been termed the impersonation of the animal 

 itself. Observe, first, how the brain is situated 

 within the head on the dorsal surface of the body ; 

 from whence it gives off nerves to the eyes and an- 

 tenna, the organs of sight and touch. In the rear it 

 gives origin to a secondary nervous system, which is 

 entirely distributed through the proboscis and oeso- 

 phagus ; in the front another special system supplies 

 the lips, and no doubt communicates to them the pro- 

 perty of taste. On the sides two bands are given 

 off, which form a ring round the buccal cavity and 

 are again joined together on the ventral surface 

 below the digestive apparatus. At this point there 

 is a kind of ladder-like structure, composed of two 

 cords, stretched from f)ne extremity of the body to 

 the other, and connected together in each ring by an 

 oblong mass, called a ganglion. These ganglia are 

 the nervous centres which animate the rings, any 

 one of which may be at once destroyed by the 

 removal or destruction of the ganglion belonging to 

 it. From each of these centres, five nervous trunks 

 are given off on each side, which distribute their 

 branches to the intestine, and to the muscles of the 



* The brilliant colours of the Eunice and other Annelids are due 

 to a phenomenon of polarization caused by the interlaced arrange- 

 ment of the very delicate fibres of the epidermis. 



