THE STRUCTURE OF THE EYEBALL 



513 



the presence of certain specific toxins in the blood. The com- 

 monest type is one in which there is contraction of the pupil on 

 accommodation, but little or no reaction to the stimulus of the retina by 

 light. This condition of the pupil is called the Argyll-Robertson pupil. 

 The seat of the injury appears to be either .in the fibres travelling from 

 the retina? to the anterior corpus quadrigeminurn or those coming from 

 these centres and travelling to the 3rd nerve nucleus. 



ACTION OF DRUGS. The following Table shows the action of certain 

 drugs on the pupil :. 



TABLE TO SHOW ACTION OF DRUGS ON PUPIL. 



