108 



" If the brain, then, is the seat of the mental power, of 

 intellect or consciousness in the human race, is it not fair to 

 assume that it is so in all the lower animals, as long as we 

 have no reason to believe to the contrary ? 



" The nervous system of all animals contains two parts at 

 least ; one part is devoted, so to speak, to the transmission of 

 impressions, and the other to their reception; their relation 

 being to each other the same as the wires of a battery to 

 the persons who work them. 



" The one part is white, the other is grey. 



" The grey is the most important, and its quantity is inva- 

 riably proportioned to the work it has to do. 



"We may farther consider that one portion of the grey 

 matter is devoted to psychical, the other to organic or cor- 

 poreal purposes. 



" In the vertebrated animals the largest quantity is always 

 accumulated in the brain — the seat of sensation, intellect, &c. 

 Its quantity there is in direct proportion to the intellectuality 

 of the creature, and the amount of physical or bodily work it 

 has to perform. 



" In fishes the smallest quantity of grey matter exists, and 

 it is disposed in such a way, that we have reason to believe 

 they can have but little intelligence ; they appear to have 

 what is simply requisite for the performance of the animal 

 functions. 



" Below fishes, we find invertebrate animals which possess no 

 brain proper, and whose nervous system consists of a number 

 of ganglia containing grey matter in proportion to the amount 

 of organic functions to be performed. 



" It is then by no means too much to assume, that they do 

 not possess any mental or intellectual power. 



" The supraesophageal ganglion, which is considered as the 

 analogue of the brain, does not appear to possess any other 

 power beyond that of regulating or controlling the bodily 

 functions. 



