642 



peripheral end only was stimulated. On the other hand stimulation 

 of the central end of the severed nerve still produced contraction in 

 the muscle (7). The contraction excited by stimulation of the cervical 

 nerve is therefore reflex in character and depends on the integrity 

 of the spinal accessory. 



M. M. Lesbre and Maignon have repeated Chatjveau's experi- 

 ments on the brachio-cephalicus in dogs, horses and cows, and find 

 that in horses and cows the spinal accessory is entirely motor in 

 function, while the cervical supply is purely sensory. Section of the 

 spinal accessory produces paralysis of the brachio-cephalicus and 

 ataxia of the shoulder (8). 



Clearly, then, there is a sensory-motor circuit in the nerve supply 

 to the brachio-cephalicus. This circuit may be interrupted by damage 

 to the motor or the sensory nerve. Damage to the motor nerve 

 produces paralysis combined with ataxia, as the afore -mentioned 

 writers have shown. In the light of our veterinary cases damage to 

 the sensory nerve results in ataxia only. 



Our experiments show that forcible abduction of the fore -limb 

 produces damage to the cervical supply and the resulting condition 

 of the animal depends on whether these nerves convey the sensory 

 branches only to the muscle, as in the horse, or whether they convey 

 both sensory and motor branches, as in the giraffe. 



I conclusion, I would offer my best thanks to Messrs. Jenkisok 

 for permission to publish these cases, and for help in the investigation. 



I would also acknowledge my indebtedness to Mr. Bailey, keeper 

 at Belle Yue, for his help in enabling me to obtain the facts con- 

 cerning the giraffe and for his kindness in reporting to me any 

 changes which his traiued eye has noticed in the condition of the 

 animal. 



Summary. 



1. Lesions of the cervical nerve supply to the brachio-cephalic 

 muscle may be produced by forcible abduction of the 

 fore-limb. 



2. An accident of this type occurring in a horse will produce 

 ataxia of the shoulder, but not permanent paralysis of the 

 brachio-cephalicus. 



This is due to the fact that the cervical nerves convey 

 only sensory branches to the muscle. 



