192 COLOE-BLINDNESS IN ITS RELATION TO 



5. — APPRECIATION OP THE CAPACITY OP EXAMINEES. 



The method of scrutiny here described is able to detect, as we have 

 seen, not only complete or incomplete color-blindness, but a feeble chro- 

 matic sense. Moreover, it has been proved that there is a perfect grada- 

 tion from complete color-blindness on the one side to the normal chro- 

 matic perception on the other. The question then naturally arises, from 

 our practical point of view, whether it is possible to draw a dividing 

 line between the kinds and degrees of defective color- vision which would 

 except those who could not cause any inconvenience to the railway ser- 

 vice, and, in case of an affirmative answer, where such limit is to be 

 found. 



It must first be remembered that in the existing state of things, these 

 questions neither can nor ought to be settled in the same manner in 

 every case, since the examination is intended for individuals of two dif- 

 ferent classes; 1st, the aspirants for railway employment; and, 2d, the 

 employes, or those already in service. 



A. Aspirants. — We must bear in mind that in Sweden, according to 

 the regulation in force there for the management of state railways (fol- 

 lowed also, as far as we know, on the private lines), it is required that, 

 in order to be admitted, each applicant "prove by a certificate from a 

 physician that he is exempt from any kind of infirmity, disease, or defect 

 of conformatioa that could be prejudicial to the exercise of his functions," 

 and also, that among these defects of conformation, in connection with 

 signals, are reckoned the defects of the chromatic sense, to which the 

 managers have especially directed the attention of the physicians at- 

 tached to the lines. 



According to the principles we have stated, the greatest severity 

 should be observed in this case, or, in other terms, the least defect in the 

 sense of colors should be a sufficient ground for rejection. 



B. Persons already in service. — We must here ask ourselves if there 

 is no necessity to modify the limit we have just traced, in order to carry 

 out the principle we stated before, namely, that it is necessary to adopt 

 less severe rules to elimiuate from the service those who are already 

 employed. We here encounter great difficulties, and it will be seen that 

 it is not possible to settle the question summarily, that is, that a well- 

 defined limit cannot be traced. In such cases, the physician should 

 always, when he discovers a defect in the chromatic sense, give a certi- 

 ficate which should indicate its nature. These indications include, as we 

 have already said, the diagnoses : complete red-blindness, complete green- 

 blindness, incomplete color-blindness, or a feeble chromatic sense. 



We are convinced that every case of complete color-blindness of both 

 kinds, as well as every case of incomplete of the higher degrees, should 

 be immediately dismissed. But as regards those who may be retained, 

 it is clear that the first question concerns those who, at the time of the 

 trial, were regarded in the diagnosis only as having a feeble chromatic 

 sense, and then those who in the first test merely confound gray with 



