6434 Reason and Instinct. 



whole and a part depending on the class in the animal series which 

 may happen to be under discussion — is the mechanical engine through 

 which Instinct acts upon the other faculties of the animal. Indeed a 

 good deal has been already done in the direction of deciding what 

 particular parts of the brain are connected with such and such 

 Instinctive tendencies and operations : thus Sir B. Brodie says, "Those 

 bodies situated in the base of the brain, to which in the human subject 

 we give the names of medulla oblongata, cerebellum, thalaml, corpora 

 striata and tubsrcula quadrigemina, and the parts corresponding to 

 these in other vertebrate animals, are connected with that class of 

 phenomena which belong to the animal appetites and instincts." — 

 p. 175. 



We proceed then with our endeavour to show that the Comparative 

 Anatomy of the brain, from the most rudimentary to the most complete, 

 in the various orders of animal life as contrasted with the different, 

 but corresponding, degrees of development of Instinct and Intelligence 

 jointly — displayed as each order in succession comes under obser- 

 vation — is not simply very interesting, but very significant likewise. 

 And this, too, notwithstanding the fact that the sum-total of our 

 information on the entire subject is confessedly, in many respects, 

 meagre and unsatisfactory to a degree. 



Commencing with a very brief notice of the nervous system of the 

 Radiata, we find no traces of a brain or even of a brain substitute, 

 properly so called. In some of the higher Echinoderms there is an 

 apparent advance in the nervous apparatus and an occasional glimmer 

 of something which looks like incipient Instinct. The instances 

 adduced by Mr. Couch (111. Instinct, p. 12) are not only interesting 

 but contain one more proof, if proofs were wanted, how invaluable 

 accurate and abundant information as to the habits and peculiarities 

 of the lower animals would be to us ; as they also suggest the more 

 than possibility that Physiology has still much more to do than it has 

 already done, in revealing to us the complete structure and uses of 

 the nervous system and its separate components, especially in these 

 lower classes : he says, " The class of star-fishes (Asteriadce) show 

 the earliest manifestation of an advance towards a true nervous 

 system : for though seemingly very inert and destitute of intelligence 

 they display some sagacity in the discovery and choice of food, as 

 well as in the manner of seeking it. The common sea-hog or sea-egg 

 (Echinus Splicera) though apparently destitute of every sense, or possi- 

 bility of regarding external objects by sight or hearing, will travel up 

 the rods of a crab-pot, enter the opening, descend within, mount again 



