767 



through the stitniilns of this convergence, and with the iitriiost 

 exertion, 8 inyodioptries, and can tlierefore accommodate at M ; it 

 however, the muscle is paralysed in the sliglitest degree, it will 

 contract less strongly through this same stimulus, e.g. only 7;^ 

 myodioptries, and will therefore accommodate at H. 



By determining the relative accommodation, we can iherefore 

 detect the slightest paralysis of the muscle in an individual of whom 

 the accommodation-figure is known (question d). 



To see if the myodioptrie is a constant value, we paralyse the 

 muscle to a certain degree, for instance so that on converging 6 

 metreangles, accommodation is only possible as far as Q; the muscle 

 then has an action of 7 instead of 8 myodioptries; if all myodiop- 

 tries are of equal value, then the muscle only possesses 7/8 of its 

 power and is for l/8th paralysed. We control this by measuring 

 the relative accommodation and determining the degree of paralysis 

 for the same paralysis and other conveigencies too. 



If one constantly finds the same degree of paralysis, so that on 

 converging 4 metreangles an accommodation only takes place up 

 to y =rr 5i myodioptrles, instead of 6; and on converging 3 metre- 

 angles, there is only an accommodation to U = 3^ myodioptries 

 instead of 4; then the paralysis appears to be constantly 1/8. One 

 can control this with as many degrees of paralysis and convergen- 

 cies as one wishes, so that question b, whether the myodioptrie is 

 a constant value in one particular person, can be definitely solved. 



To determine the course of the lines of the relative near and far 

 points in the latent area, one paralyses the accommodationmuscle 

 to a certain degree, say the half, so that one finds by convergence of 

 two metreangles (in fig. 1) a greatest accommodation of 2 D., instead 

 of 4 D. ; 3 D. instead of 6 D., on converging 4 m.a. ; and 5 D.. 

 instead of 10 D., with a convergence of 8 m.d.; if, now, on 

 converging 12 metreangles a greatest accommodation of 7 D. is 

 reached (to Y in fig. 1), then one may say that the half- paralysed 

 muscle contracts 7 myodioptries with this stimulus; the JKirmal 

 muscle would therefore have reacted with 2 7 = 14 myodioptries, 

 so that the relative near point with a convergence of 12 metreangles 

 would lie at W., on the ordinate of 12 and the abscis of 14. 



If, with a convergence of 14 metreangles, one finds a greatest 

 accommodation of 8 D., (to X in fig. 1), then the healthy muscle 

 would be able to contract 16 myodioptries, in answer to this stimulus. 

 thus fixing the point Z on the abscis of 16 and the ordinate of 14. 



If with a convergence of 18 metreangles one finds an accommoda- 

 tion of 10 dioptries, then point j on the abscis of 20 myodioptries is 



