768 



determined. In this manner one can determine in the latent area 

 as many pointjs of the line of relative near points as one wislies, 

 with different convergencies and different degrees of paralysis, and 

 so plot out the entire line. 



The conrse of the line of relative far points in the area of latent 

 ciliary muscle contraction, is determined in the same manner, so 

 that question ƒ. is solved. 



We determine the strength of the accommodation muscle in the 

 following manner : 



When the area of relative accommodation has been completely 

 ascertained, the muscle is paralysed. Supposing that in the individual 

 of fig. 1, the accommodation muscle is paralysed for V^''' pai't ; 

 the absolute near point is now determined; if this still lies at a 

 distance of 10 cm., then one can say that '/, "f the muscle-power 

 produces a contraction of at least 10 myodioptries, the total muscle 

 power is therefore at least 4/3 X 10 = 13 1/3 myodioptries. 



If the paralysis is 1/3 while the accommodation remains 10 I)., 

 then firstly one may consider question a. as answered; for a partially 

 |)aralysed muscle can evidently give the greatest possible accom- 

 modation, so the strongest possible contraction is not necessary, and 

 secondly 2/3 of the muscle-power produces a contraction of at least 

 10 myodioptries, the muscle-power is therefore at least 3/2>10=rl5 

 myodioptries. 



If again witii a paralysis of ^ an accommodation of 10 D. is 

 reached then the power is at least 20 myodioptries. But if, on para- 

 lysing the muscle for one third of its power, only 8 D. accom- 

 modation is reached, then the power is 3 8 = 24 myodioptries. 



Control is obtained by further paralysis; if, after paralysing three 

 quarters of the power, 6 D. accommodation is reached, then the 

 total power is 4X6 = 24 myodioptries; if there is still an accom- 

 modation of 4 D., after the muscle has been paraly.sed to '/o. ^''6" 

 the power is 6 X 4= 24 myodioptries, etc., so that the result obtained 

 can be controlled by as many observations as one wishes. 



If all the values obtained coincide sutlficiently, then one lias not 

 only determined the muscular power, but has also proved that the 

 niyodioptrie has a constant value and that the method must be 

 correct, otherwise the values could not constantly be found to coincide. 



A curve of the paralysing action of £v substance can he obtained 

 by first determining the total power of the muscle in a certain 

 individual, then dropping the paralysing substance in the eye, and 

 determining the power again, at regular intervals, the results being 

 plotted out in a scheme. 



