332 Veterinary Medicine. 



The strength of the solution of atropine is an important con- 

 sideration. Donders found that i : 120 of water produced a full 

 effect, while Jaarsnia obtained the full eflfect in one hour from a 

 drop of a solution of one to twelve hundred of water. The action 

 on carnivora (dogs and cats) is equivalent to that on man, while 

 on the herbivora (rabbit, horse, ox, sheep) it is somewhat less, 

 and on birds very slight indeed. On diseased eyes a large amount 

 may be required, and with senechia (adhesion of the iris to the 

 capsule of the lens) dilatation may be impossible. The full 

 effect may last 24 hours, and accommodation may remain very 

 imperfect for 1 1 da^^s. 



The direct action of atropine on the eye is shown in dilatation 

 of the pupil of the frog after the eye has been detached from all 

 connection with heart or brain, by excision. It acts also in the 

 normal .system through reflex nervous action, since, after division 

 of the .sympathetic trunk going to the e3'e, that eye does not di- 

 late so much under atropia as the opposite eye. 



Atropine is usually employed by lodging a drop in the pouch 

 of the conjunctiva (inside the lower lid), and from this it makes 

 its way into the aqueous humor, for if that liquid is transferred to 

 the conjunctiva of another animal it causes dilatation. Puncture of 

 the cornea with evacuation of the aqueous humor lessens the action 

 of the atropine. Atropine dilatation is increased by following it 

 with cocaine which causes contraction of the iridian vessels, the 

 antithesis of the dilatation of the vessels which occurs when the 

 cornea is perforated and the pressure of the aqueous humor is re- 

 moved. 



Atropine is one of the most potent poisons and must be used 

 with caution especially in the carnivora and omnivora. The 

 danger lies not alone in the absorption from the conjunctiva, but 

 also from the e.scape of the liquid through the lachrymo-nasal 

 duct, to the nose and later to the actively absorbing mucosse of 

 the lungs and stomach. 



The .symptoms of general poisoning are : rapid pulse, vertigo, 

 weakness of posterior limbs, general prostration and thirst or 

 dryness of the throat. 



Homatropine is an oily liquid produced by the action of 

 muriatic acid on the cyanate of atropine. With hydrobromic 

 acid it forms a readily crystallizable salt, the solution of which 



