DEUGS WHICH ACT UPON THE NERVOUS SYSTEM 483 



Its action is that of a powerful sedative to the spinal cord, allaying 

 its excitability, paralysing voluntary muscles, and reducing the sensibility 

 of the skin. It has been found to control the spasms of tetanus, and 

 its active principle, eserin, is employed to contract the pupil of the eye 

 in opposition to belladonna or atropine, when, as has already been 

 pointed out (see Belladonna), it is desirable to keep the intiamed iris 

 from contact with parts to which it may adhere. 



In cases of impaction of the bowel, it has the reputation of exciting 

 peristaltic action and facilitating the removal of the offending matter 

 more quickly than any other agent. 



Hemlock {Conium maculdttim). — The " hemlock rank ", which the 

 cow is recommended in our nursery rhymes not to eat when " growinsr 

 on the weedy bank ", was a favourite poison with the ancients, and the 

 one by which Socrates cut short his useful life. It is not much used 

 as a horse medicine, although under some circumstances it is known tO' 

 produce very powerful effects upon the animal. 



Cocaine, the active principle of Coca , or Cuca, has pi'oved a great 

 boon to the veterinary practitioner, and especially in connection with 

 surgical operations, which have not only been rendered easy of perform- 

 ance by it, but have also been deprived of mucli of the danger that used 

 to attend them. 



A four-per-cent solution dropped into the eye enables one to examine 

 it, and remove any hay seeds or other foreign bodies, while the anaes- 

 thetic effect may be continued long enough to perform many operations. 

 Injected under the skin, firing and cutting operations can be performed 

 with a minimum of pain and restlessness on the part of the animal. 



ANTISEPTICS 



Antisejitics are agents which either arrest or prevent putrefaction or 

 decomposition. The word is derived from two Greek words — anti, 

 against, and sepene, to rot. Decomposition, in the sense here understood, 

 is due to the presence of minute organisms, and true antiseptics, being 

 inimical to their existence and multiplication, render its occurrence im- 

 possible. 



By the employment of these agents in one or another of their various 

 forms, surgery, both in its application to man and the lower animals, 

 has been revolutionized. Not only by their use have operations which 

 formerly resulted in great mortality been stripped of their danger and 

 rendered safe, but others of a more formidable and important character 

 liave been rendered possible and in a large measure successful. So much. 



Vol. II. 652 



