3G8 SJR THOMAS R. FRASER AND MR A LISTER T. MACKENZIE ON 



Results of a similar kind were obtained with more dilute solutions (e.g. 1 in 1000), 

 but longer contact with the extract was required to produce them. 



Further evidence of the action of this extract on sensory nerves was obtained by 

 applying a solution of it to the cornea of the rabbit. The next experiment typifies 

 these results. 



Experiment XL VII. — It was found that a light touch with the point of a blunt 

 stylette applied to the centre of the cornea of either eyeball of a rabbit caused the 

 animal to close that eye rapidly and momentarily. The transverse diameter of each 

 pupil was 8 mm. Of a solution of the extract of S. sarrnentosus in distilled 

 water (l to 500) one-tenth of a cubic centimetre was placed on the right eyeball. In 

 3 minutes, the reflex in each eyeball was equal and unchanged. In 8 minutes, the 

 reflex in both eyeballs was still equal and unaltered, and both pupils measured 7 mm. 

 in transverse diameter. In 15 minutes, no reflex movement occurred when the right 

 eyeball was lightly touched with the stylette, but the left eyeball was as sensitive as 

 before ; the right pupil was 7 mm. in transverse diameter and the left was 6 mm. 

 In 20 minutes, the right cornea could be depressed with the stylette without any reflex 

 movement following ; the reflex in the left eyeball was acute and the transverse 

 diameter of each pupil was 6 mm. In 30 minutes, the point of the stylette could be 

 drawn lightly almost half-way across the right corneal surface without eliciting a 

 reflex ; less gentle application caused partial closing of the eyelids ; on the left side 

 the corneal reflex was acute ; the right pupil was 9 mm. and the left pupil 8 mm. in 

 transverse diameter. In 40 minutes, each pupil was 7 mm. and the state of the 

 corneal reflexes was as last described. In 50 minutes, the right cornea could be gently 

 touched and even slightly depressed by the stylette without causing reflex closing of 

 the eyelids ; the corneal reflex in the left eyeball was acute ; both pupils measured 

 8 mm. in transverse diameter, and the anaesthesia seemed to be passing off. In 2 hours 

 10 minutes, the right cornea was less sensitive than the left, whose reflex was acute; 

 and the transverse diameter of the right pupil was 8 mm., and of the left 7 mm. In 



3 hours after the application of the extract, the right corneal reflex was sluggish and 

 the left was still acute ; and both pupils measured 8 mm. in transverse diameter. In 



4 hours, the right cornea was insensitive to very light touches only, but less so than 

 it had been an hour earlier, while the left cornea was acutely sensitive ; and both pupils 

 were 7 mm. in transverse diameter. In 5 hours, the right cornea could still be touched 

 very lightly without a reflex following, but heavier touches caused reflex closing of the 

 eyelids ; the left corneal reflex was acute ; and each pupil was 9 mm. in transverse 

 diameter. In 7 hours, the lightest touch on the right cornea with the stylette caused 

 a partial closure of the eyelids, but the left cornea "was still more sensitive, and each 

 pupil measured 9 mm. In 23 hours after the application of the extract, each pupil 

 measured 8 mm. in transverse diameter ; the corneal reflex had reappeared in each 

 eyeball, but still very light touches with the stylette on the right cornea failed to 

 elicit a reflex. The only evidence of irritation was the occurrence of several quickly 



