72 INSTINCT, REASON, ETC. 



To continue our definitions : " Reason or intelligence is 

 the faculty which is concerned in the intentional adjustment 

 of means to ends. It therefore implies the conscious know- 

 ledge of the relation between means employed and ends 

 attained, and may be exercised in adaptation to circumstances 

 novel alike to the experience of the individual and to that of 

 the species." 



The seat of this faculty is the cerebrum, or great brain ; 

 and in proportion to the intelligence of the individual do we 

 find the size of this organ ; or, to put it more accurately, 

 do we find the quantity of grey matter and the size of brain 

 surface ? This latter increase may be attained by increase in 

 number and depth of the convolutions on the surface of the 

 brain. The convolutions of the brain of a Herbert Spencer, 

 or a Tennyson, are much deeper and more complex than 

 those of the brain of an aboriginal Australian; the brain of the 

 latter, however, excels in this respect, though not to the 

 same extent, that of a gorilla ; so between the gorilla and 

 the dog, the dog and the rabbit, and so down the scale of 

 organised beings, until we find not only smoothness of surface 

 and contraction in proportion relatively of large to lesser brain, 

 but a gradual diminution, till the only representative of this 

 important organ is a mere spot in comparison with the 

 aggregate of the other cerebral substance : as in the turtle for 

 instance, going further down it gradually diminishes till we 

 get to creatures that do not possess any. Our diagram Avill 

 illustrate my meaning. All those portions of the cerebro- 

 neural axis that are concerned in the physical life of the 

 creature and the preservation of the species are well developed, 

 while the part concerned in the psychical is a mere fore- 

 shadowing as compared to its purely brute inheritance. Thus, 

 retracing our steps and ascending the scale of creation, we 

 find there is a time in the life history of organised beings 

 when, 1st, purely reflex actions begin to be complicated by 

 others wherein consciousness plays an important part, and 

 there is simultaneously a proportionate structural addition; 

 and 2nd, when a power of co-ordinate thought is accompanied 

 by an addition superimposed to the already existing cerebral 

 structures. It is in this same power of co-ordinate thought, 

 and his " potential power to progress " in it that man stands 

 out from the other primates a landmark in Evolution, the 

 most wonderful product of causal effects, " the roof and crown 

 of things." With the advent of man as man, when psychical 

 development came to relegate physical to a less important 

 position, when brain substance acquired the power to progress 



