182 PROFESSOR WARTMANN ON DALTONISM, 
sation does not take place, or that the weakness of the impres- 
sion may be such as to act as a cause of producing a habit of 
inattention, from which results the incapacity of conceiving the 
recollection of it. M. Prevost, who relates the explanation of 
Stewart, states that he does not adopt it*, but declares himself 
a partisan of that which I shall proceed to explain. 
Dr. Dalton+ concludes, from his personal observations, that 
the humours of his eyes and of those of his pupils are coloured 
bluet. He admits that this coloration must be peculiar to the 
vitreous humour, for if it had affected another part of the organ 
it would have been discovered by an external inspection. In 
spite of the attempts of the author to explain by this theory the 
different facts of vision which he described, in spite of the rea- 
sonings of Prof. Prevost to obviate the objections (apparent ac- 
cording to him) which have been made thereto, it does not seem 
to me that it can be admitted. First, it could not explain the 
diversity of names given to the same colour by different dalto- 
nians: secondly, if the passage of the luminous rays through a 
blue medium sufficed to produce daltonism, the habitual use of 
blue glasses for spectacles would have long ago confirmed this 
hypothesis, against which it forms on the contrary a very strong 
argument. It is known that old men in whom the crystalline 
takes an amber tint, continue to see objects with their proper 
colours. Lastly, the most distinguished oculists and surgeons of 
Switzerland, Germany, England, France and the Low Countries, 
whose opinions I have been able to collect, are unanimous in not 
quoting any case of this blue coloration of the vitreous hu- 
mour; and the best analytical works that we possess upon the 
mechanism and composition of the eye, the works of Thomas 
Young$, of Chenevix||, of Nicolas**, of Berzeliust++, &c., all 
* Dr. Elliotson likewise rejects this hypothesis. See Froriep’s Neue Notizen, 
1839, No. 247. 
t Mem. of Manchester, vol. v. p. 30. 
{{ From a dissection of Dr. Dalton’s eyes by Dr. Ransome of Manchester, it 
is now certain that the vitreous humour of both was not blue but colourless.— 
Paes Young. On the Mechanism of the Eye, Phil. Trans. 1801, 
part 1, p. 33. Bibl. Univ., tome xviii. p. 225. 
| R. Chenevix. On the Humours of the Eye, Journ. of the Roy. Institu- 
tion. Bibl. Brit., tome xxii. p. 345. 
** Nicolas, Dr. and Prof. Mémoire Analytique sur les différentes Humeurs de 
V Gil, dans les vues de découvrir leur nature et les causes qui peuvent donner lieu 
a cette maladie désignée sous le nom de Cataracte. An. de Chim., tome liii. p. 307. 
++ J. Berzelius. Vues générales sur la composition des Fluides Animauz. 
Medico-Chirurgical Transactions of London, t. iii. Bibl. Brit., t. liv. p. 27. 
