390 HEALTH AND DISEASE 



govern the complex muscular movements of mastication, insalivation, 

 deglutition, winking, breathing, with its accessory movements of coughing 

 and sneezing. 



The corpora striata and optic thalami, or great ganglia, at the base of 

 the brain, are probably the regions where consciousness first appears, con- 

 sciousness of the different forms and kinds of nervous stimuli, and the 

 place where conscious efforts or muscular movements are made in response 

 to them. These ganglia are particularly connected with the sense of sight. 

 They are relatively large in the horse, for whilst in man their proportion to 

 the brain may be taken as 5 : 100, in the horse it is 13 : 100. 



The outer layer or cortex of the brain is the highest centre of all. It is 

 the seat of the emotions of judgment, memory, reason, and the will. We 

 have seen that it consists of gray substance containing many nerve-cells, 

 which give off fibres that extend to and from the ganglia below and to the 

 periphery of the body. It has often been exposed as the result of accident, 

 and has uniformly been found to be insensitive to direct stimulation, so 

 that large portions have been cut away without pain being experienced 

 even in man. Evidence has accumulated during the past few years, show- 

 ing that the several convolutions have definite functions, so that one set is 

 concerned with the initiation of movements of the head and neck, another 

 with those of the fore-limbs, and others with those of the trunk and hind- 

 limbs. Special lobes of the brain are also connected with the several 

 senses, the occipital lobes being especially connected with the visual sense, 

 the temporo-sphenoidal lobes with the hearing. 



The horse appears to be an animal endowed with a remarkable power of 

 association of definite movements with certain mental stimuli, and with an 

 excellent memory. It will stop before tlie customers' doors, the sound of 

 the rider's voice will cheer and direct it, and in military evolutions the 

 bugle-cialls are quite as well known l)y the horse as by its rider. It 

 will remember events that are long past. It enters into the spirit of 

 trials of speed and strength, and of games, as those of polo and steeple- 

 chasing, with the utmost zest and enjoyment. 



The horse owes his proud position with the dog, as the friend of man, 

 to his docility, his gentleness, his great muscular strength and swiftness. 



