Marvels of Pond-Life. 85 



bellum or spinal cord."* The superior ganglion gives 

 off nerves to the antennae and eyes, the lower one to the 

 mandibles, &c. So far as is known the insects that 

 exhibit the most intelligence have the largest and best 

 developed brains. 



A special volume would be required for anything like 

 a complete examination of the little which is known on 

 this subject, but these few remarks may assist the 

 microscopic beginner in examining the movements of 

 his subjects, and guard against the error of referring to 

 reason and volition those which are, probably, either the 

 direct result of stimulants applied to the surface (as in 

 nerveless creatures), or the indirect (reflex) result of 

 such stimulants in beings like the rotifers, who have a 

 nervous system ; or the result of sensations, which 

 excite actions without previously referring the matter 

 to the decision of a will. It must not, however, be 

 too readily assumed that the behaviour of creatures 

 possessing distinct organs is entirely automatic; and 

 we must not forget that even the best physiologists 

 know very little concerning the range of functions 

 which the nervous ganglia of the invertebrata are able 

 to discharge. 



* ' Anatomy of Invertebrates/ Burnett's trans. 



