MENTAL CONSTITUTION OF ANIMALS. 171 



t€.rais This view agrees with what all observation teach- 

 es, that mental phenomena flow directly from the brain. 

 They are seen ^o be dependent on naturally constituted 

 and naturally conditioned organs, and thus obedient, like 

 all other organic phenomena, to law. And how wondrous 

 must the constitution of this apparatus be, which gives us 

 consciousness of thought and of affection, which makes 

 # us familiar with the numberless things of earth, and ena- 

 bles us to rise in conception and communion to the coun- 

 cils of God himself! It is matter which forms the me- 

 dium or instrument — a little mass which, decomposed, is 

 but so much common dust ; yet in its living constitution, de- 

 signed, formed and sustained by Almighty Wisdom. How 

 admirable its character ! how reflective of the unuttera- 

 ble depths of that Power by which it was so formed, and 

 is so sustained ! 



In the mundane economy, mental action takes its place 

 as a means of providing for the independent existence and 

 the various relations of animals, each species being fur- 

 nished according to its special necessities and the demands 

 of its various relations. The nervous system — the more 

 comprehensive term for its organic apparatus — is various- 

 ly developed in different classes and species, and also in 

 different individuals, the volume or mass bearing a gene- 

 ral relation to the amount of power. In the mollusca 

 and Crustacea we see simply a ganglionic cord pervading 

 the extent of the body, and sending out lateral filaments. 

 In the vertebrata, we find a brain with a spinal cord, and 

 branching lines of nervous tissue.* But here, as in the 

 general structure of animals, the great principle of unity 

 is observed. The brain of the vertebrata is merely an 

 expansion of one of the ganglions of the nervous cord of 

 the mollusca and Crustacea. Or the corresponding gan- 

 glion of the mollusca and Crustacea may be regarded as 

 the rudiment of a brain, the superior organ thus appear- 

 ing as only ? further development of the inferior. There 

 are many ^acts which tend to prove that the action of this 

 appaiatus is of an electric nature, a modification of tha*" 

 surprising agent which takes magnetism, heat, and light, 

 as other subordinate forms, and of whose general scope in 



* The ray, which is considered the lowest in the scale of fishes, 

 or next to the crustaceans, gives the first faint representation of a 

 brain in certain scanty and medullary masses, which appear at 

 werely com posed of enlarged origins of the nerves. 



