15 



20 



40 

 50 



780 DR FRASER ON THE PHYSIOLOGICAL ACTION 



myositic agent than opium — is thus not only of great intrinsic interest, but also 

 likely to be of considerable importance in explaining its action on the iris. In 

 the experiments that were undertaken for this purpose, the condition of the 

 pigment-cells also was observed. 



Experiment CI. 



The spinal cord of a light-coloured, large frog was divided between the first vertebra and 

 the occiput ; and, thirty minutes afterwards, a portion of a web was placed on the stage of a 

 microscope. 



An artery and three branches were selected for examination (A, B, C and D) ; and during 

 ten minutes, their diameters occupied pretty constantly the following divisions of an eye-piece 

 micrometer : — 



A = 3;B = 2;C = 2;D = l-5. The pigment-cells were diffusely stellate. 



A small drop of filtered watery solution of extract was placed on the web. 



( Current of blood 

 In 2 minutes, A = 30 ; B = 2'0 ; C = 20 ; D = 15. Pigment-cells stellate, < seems rather 



(^ more rapid. 

 A = 30 ; B = 25 ; C = 2-5 ; D = lo. 



A = 3-5 ; B = 30 ; C = 3-0 ; D = 1-5. „ concentrating. 



A = 40 ; B = 30 ; C = 30 ; D = To. „ concentrated : no rays. 



A = 40 ; B = 30 ; C = 3-5 ; D = 2-0. 

 A = 40 ; B = 30 ; C = 35 ; D = 20. „ diffusing a few rays. 



( rather more diffuse than 

 1 h. inin. A = 40 ; B = 30 ; C = 3"5 ; D = 20. „ < at commencement of 



(, experiment. 



-, , A A , A TJ o A n o - i^ on f m nearly extreme ) Circulation 



1 „ 10 A = 40 ; B = 30 ; C = 3o ; D = 20. „ j ^^ | free 



A second drop of the solution was placed on the web. 



A = 40 ; B = 3-0 ; C = 3-5 ; D = 20. Pigment-cells concentrating. 



A = 40 ; B = 3-0 ; C = 3-5 ; D = 2-0. „ stellate. 



A = 4-0 ; B = 3-0 ; C = 3-5 ; D = 2-0. „ again diffusing. 



A = 4-0 ; B = 30 ; C = 35 ; D = 2-0. „ in extreme diffusion. 



A = 40 ; B = 30 ; C = 35 ; D = 2'0. 



Experiment CI I. 



An artery and two branches (A, B, C) and a capillary (D) were selected in the web of 

 frog, which was prepared as in the preceding experiment. Their diameters were found to be the 

 following — A = 7;B=65;C = 4;D = 1: while the pigment-cells in the field were in a state 

 of extreme concentration, there being no rays visible. 



A drop of a filtered, strong solution of extract was placed on the web. 



t 1rt ■ , A nT) r. r-p. -, f Pigment-cells in extreme concentration. Cir- 

 In 10 minutes, A=9;B=8;C = 5;D = 1. { to -, .- . ■ 



|_ culation active. 



20 „ A = 9 ; B = 8 ; C = 5 : D = 1. j " mtr( ff. conc en tration - Cil " 



( culation active. 



40 „ A = 9 ; B = 8; C = ff; B = 1. „ stellate. Circulation languid. 



The observations were continued until two hours after the application ; and, up to that 

 time, no further change had occurred, except that extreme diffusion had appeared in the pig- 

 ment-cells. 



1 „ 



20 



1 „ 



25 



1 „ 



26 



1 „ 



30 



1 „ 



35 



2 



30 



