Memory. 667 



visceral muscles, the circulatory system, &c. The action is more or 

 less indirect, and made up by the combination of several stimuli. It 

 may be called Excito Motor. Third is the Cerebellum, the balancing' 

 and co-ordinating action of which has been called Automatic. Fourth 

 is the machine made up of the Basal Ganglia the optic lobes, thala- 

 mus, striatum, &c. The stimuli operating this machine are chiefly de- 

 rived through the senses, not only touch, which is chiefly concerned in 

 the reflex actions of the cord, but sight, smell, taste and hearing as 

 well. This action is therefore denominated Sensori- Motor. Fifth is the 

 cerebrum. The motor actions starting here arise from stimuli which de- 

 pend primarily on the senses as much as those of the centers below. 

 But the cerebrum is pre-eminently an organ of memory, and the sensory 

 stimuli become cumulative, their effects often lasting for many years. 

 These memories, and the new conceits that are formed out of them, con- 

 stitute our ideas, and they become largely concerned, with or without 

 the present or immediate sensory impressions, in forming the motor 

 stimuli of the cerebrum, from which circumstance these stimuli are 

 called Ideo-Motor. 



"While these terms are convenient for purposes of study, we must bear 

 in mind that the} 7 do not indicate any radical or essential difference of 

 principle in the classes of action they describe. All the stimuli are sen- 

 sory to begin with. The lower ganglia are influenced by but few of the 

 senses, the cord by only one or two. The higher ganglia are moved by 

 all the senses. The basal ganglia depend for their stimulations chiefly 

 on the sensory impressions of the moment, a very small proportion be- 

 ing derived from the memory of past ones. The impulses sent from 

 the cerebrum may be made chiefly from the memories of past sensory 

 impressions. Thus, all these machines depend on the same motive stim- 

 ulation of external forms of force by way of the sense organs, and the 

 difference in their actions depends on their susceptibilit}" to be set in mo- 

 tion by a larger or smaller number of these sensory forces. 



At birth, every cell of the brain is connected by nerve fibres with 

 some certain sense organ. We have seen that the different sense organs 

 each have their definite patches of brain, and the practical constancy 

 and uniformity among the higher mammals and men of these connec- 

 tions, prove them to be hereditary through a veiy long line of ancestry, 

 antedating the human race. 



The arms, legs, fingers, &c. , of a new-born infant are in a very in- 

 complete condition so far as use is concerned. They have not the power 

 to perform a vast number of movements which they afterwards get the 

 ability to do. But this awkwardness of the limbs is shared by a cor- 

 responding awkwardness of the cells in the spinal cord and brain. In 

 fact, the cells and the limbs together constitute a single machine, and 



