ACCIDENTS BY RAIL AND SEA. 159 



For the classification of the different forms of the defective sense of col- 

 ors, regard is generally paid to the methods of investigation, and the divi- 

 sion is governed much more by those methods than by a theory of the 

 sense of colors. But in every case it is found that the classification lat- 

 terly in use leaves room for much improvement, either because some of the 

 forms of defective color-sense not taken into account, or, on the other 

 hand, because even some cases of normal chromatic sense, wanting in ex- 

 ercise and intelligence, have been classed amongst the different kinds 

 of defective color-sense. As an instance of the first kind. Dr. Stilling's 

 classification should be mentioned, which is based upon the theory of the 

 four primitive colors, complementary two by two. According to it, there 

 could be but two kinds of color-blindness, namely : ^h-othgrUnblindhet" and 

 ^^ gelhhlauhlindheW^ {green-red-hlindness and that of blue-yelloiv). With- 

 out allowing ourselves to criticise the theory itself here, we will simply 

 remark, looking at it practically, that, on one side, this classification 

 draws no distinction between the various kinds of red- and green-blind- 

 ness. Dr. Stilling classing them as one, and that, on the other side, the 

 whole series of forms classed by us under the head of incomplete color- 

 blindness is not included in his plan. 



As an example of a classification of the last kind, the one which seems 

 universal in France, and employed by Dr. Favre and Dr. F6ris, mnj be 

 cited. It is reduced nearly to this: all those who give false names to 

 the primitive colors belong to one class j those who are only mistaken 

 in the shades, but not in the principal colors, are classed under another 5 

 and, finally, those who, after several trials, evince some hesitation in des- 

 ignating colors, form a third class. It is plain that this classification 

 gives but little idea, properly speaking, of the nature of the different 

 kinds, and that the third class must include a large number of individ- 

 uals endowed with normal sight, but who have been mistaken or hesi- 

 tated at the time of the test, in consequence of want of exercise. 



3.— COLOR-BLINDNESS IN PRACTICAL LIFE. 



Volumes might be written on this subject, if the different instances 

 of all the peculiarities presented by color-blindness, and all the embar- 

 rassment to which they give rise, were cited. We will limit ourselves 

 to a few facts here, closely connected with our really practical end, and 

 over which they exert a direct influence. To avoid being prolix, we 

 will merely remark that in alluding to color-blindness in general, with- 

 out naming one especial kind or form, we usually mean the ordinary 

 typical kinds of partial and congenital color-blindness, namely, red and 

 green. 



We must first remember that color-blindness is not a disease in the 

 sense of being attended with suffering, obliging the individual to have 

 recourse to a physician. Color-blindness, quite as well as the normal 

 sight, is a sense of color, though of another and a more simple nature. 

 He whom we call color-blind is not correctly speaking at all blind to 



