150 A MANUAL OF VETERINARY PHYSIOLOGY 



of the frightened or ' fresh ' horse, the nasal chambers the 

 whinny and neigh of pleasure, the mouth and pharynx the neigh 

 of impatience, loneliness, excitement, etc. We do not consider 

 that the guttural pouches act as resonators, and Colin obtained 

 no alteration in the character of the neigh by opening them. 



The voice of each class of animal — horse, ass, ox, sheep, and 

 pig — is so distinctive that we may recognise their presence 

 without seeing them ; yet though the larynx in all these animals 

 differs more or less, the difference is not sufficient to offer any 

 explanation as to why the sounds it emits are so entirely distinct. 

 The voice of male and female animals differs in intensity. The 

 wild neigh of the stallion is very different from the neigh of the 

 mare, and the bellowing of the bull is distinct from the ' lowing ' 

 of the cow. The operation of castration has a remarkable effect 

 on the voice, the neigh of the gelding resembling that of the mare. 



In the horse the voice is used during sexual and ordinary 

 excitement, also during fear or especially loneliness, during pain, 

 anger, and as a mark of pleasure. It is not possible to convey 

 in words the difference in the notes produced, but they are easy 

 to recognise. The horse is essentially a sociable animal ; when 

 accustomed to be in the company of others he dislikes separa- 

 tion, and shows it by persistent neighing, which is perhaps more 

 noticeable amongst army horses than any others. The neigh 

 of pleasure is often spoken of as the ' whinny ' ; the word rather 

 conveys an idea of the sound made. Sounds which can onfy be 

 described as 'screams' are often evoked during 'horse-play' 

 and temper, or by mares during oestrum. It is not a scream 

 as we know it in the human subject, but no other word conveys 

 an idea of its shrillness. If a horse cries from pain (which is 

 very rare), as during a surgical operation, the cry is a muffled 

 one and short ; it is a groan rather than a cry. 



In the cerebral cortex voice is represented in the praecrucial 

 and neighbouring gyrus of the dog, and corresponding regions 

 in other animals. Stimulation of this region leads to bi-lateral 

 adduction of the cords, which suggests that both sides of the 

 larynx are represented in each hemisphere. There is no region 

 in the cortex of the dog which, on stimulation, leads to abduc- 

 tion of the cords, though such a region is found in the cat. It 

 would appear that adduction of the cords is represented in the 

 cortex, as the muscles producing it are especially associated with 

 the production of voice, which is under the influence of the will. 

 Respiration, on the other hand, is automatic, and the abductor 

 muscles being essentially respiratory, their centre is found to 

 exist in the medulla. 



Neighing in the horse is produced by an expiration, partly 

 through the nostrils and partly through the mouth ; braying in 



