Bauhaus-Universität Weimar

Titel:
Helmholtz's treatise on physiological optics. Volume 2. Edited by James P. C. Southall. Translated from the 3rd German edition
Person:
Helmholtz, Hermann von
PURL:
https://digitalesammlungen.uni-weimar.de/viewer/image/lit39650/417/
404 
The Sensations of Vision 
[340, 341. K. 
In five cases investigated and described by König1 the disorder 
was acquired. These individuals detected no difference between a 
yellow 566-570w or a blue about complementary to it and a colour¬ 
less mixture. Moreover, special investigations with a series of colour 
combinations and matches showed that what was involved here was 
a form of reduction of normal vision. The phenomena are therefore 
in accord with what might be expected according to the Helmholtz 
theory, when the blue component is lacking. Consequently, in line 
with the nomenclature suggested above, this anomaly may be called 
tritanopia. 
Some other cases of acquired unilateral anomalies invariably of a 
similar nature have been described by Collin and Nagel.2 
In a case described by Vintschgau3 and Hering4 the anomaly was 
on both sides and congenital. Here again yellow and blue lights had 
the same appearance as composite white light. But not much difference 
could be noticed for red or green either, so that the condition was to 
some extent like that of total colour blindness. 
Other cases that may be mentioned are the one described by Piper5 
and another one by Levy.6 
With reference to colour matches, it was stated above that certain 
individual differences are apparent in persons with normal colour vision 
and also in dichromats of the same type. This fact seems to have been 
first noted by Maxwell7 who also expressed the opinion that possibly 
the explanation was a physical one and due to the yellow colouration 
of the fovea, which is different in different individuals. Quite a large 
mass of experimental work on this subject is available now, which 
tends to substantiate Maxwell’s assumption for a portion of the 
phenomena anyhow. 
At the instigation of Hering, a direct physical investigation of 
the macular pigment in the isolated human retina was undertaken by 
Sachs.8 He found that the long wave-lengths were not appreciably 
absorbed. The absorption begins in the yellow-green and continues to 
increase with decreasing wave-length. As to individual differences in 
colour matches, v. Frey and the writer9 showed that for them these 
differences in a large number of trials with all sorts of combinations 
1 Sitzungsberichte der Berliner Akademie. 1897. 
2 Zeitschrift für Physiologie der Sinnesorgane. XLI. S. 74. 1906. 
3 Pflügers Archiv. LVII. 191. 1894. 
4 Ibid. LVII. S. 308. 1894. 
6 Zeitschrift für Psychologie. XXXVIII. S. 155. 1905. 
8 Archiv f. Ophth. LXII. 3. S. 464. 1906. 
7 Philos. Transactions 1860. 
8 Pflügers Archiv. 50. S. 574. 1891. 
9 Archiv für (.Anatomie und) Physiologie, 1881. S. 336.
        

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