92 On Coloured Vision produced by Santonine. 



rest. The next day all effect had disappeared. The Santo- 

 nine employed in these experiments was extracted from Arte- 

 misia santonica, or judaica, and was absolutely pnre. 



M. de Martini, of Naples, made several experiments upon 

 his patients and his pupils, in order to ascertain whether the 

 colouration of vision, by Santonine, was the same for every 

 person, and whether the dose had any influence upon the colour 

 seen. The results obtained are certainly remarkable. An 

 invalid, who was taking Santonine as a vermifuge, invariably 

 noticed about twenty minutes * after the prescribed dose had 

 been administered, all external objects of an intense green 

 colour; whilst a student, M. Cassano, constantly saw objects of 

 a blue colour. But in the great majority of cases it was 

 observed that persons who had taken Santonine saw external 

 objects of a straw-yellow or greenish-yellow tint. The dose 

 appears to have a very decided influence upon the results. A 

 young man who took five grains of Santonine in the solid 

 form, saw external objects of a yellow colour; the dose was 

 then doubled, and thirty-six minutes afterwards, objects no 

 longer appeared green or yellow, but perfectly red; half an 

 hour later they appeared bright orange, and later still, yellow as 

 before. With M. Cassano, whether he took five grains or ten 

 grains, external objects always appeared to him of a bright 

 blue colour, whilst his fellow-student, M. Pedretti, saw objects 

 always straw -yellow. 



Another curious fact was observed, which I have looked for 

 in vain when experimenting upon myself, namely, an intermit- 

 tence in the effects of coloured vision. In some individuals 

 the apparent colouration of external objects is not permanent, 

 but intermittent ; it disappears for five or six minutes, and 

 then returns as strong as before. This I have not remarked ; 

 the greenish-yellow tint observed on all white objects and 

 flames was constant from the beginning to the end of the 

 experiments, it became gradually less intense only as the effects 

 of the Santonine went off. In no case has this remarkable 

 action of Santonine upon vision been seen to last more than a 

 day. The experiment may be safely made, even by delicate 

 persons, with a dose of five or six grains ; I do not think it 

 would be reasonable in any case to experiment on more than 

 ten grains at a time. 



The cause of this peculiar action of Santonine is the next 

 thing to be examined. M. de Martini believes that this sub- 

 stance exercises a molecular action upon the retina or optic 

 nerve; others, among whom are M. Miahle, of Paris, think 



* Twenty minutes is a very short period, unless the Santonine had been taken 

 in alcoholic solution ; I am informed that, if taken as an enema, the action is re- 

 markably rapid, and coloured vision produced in about a quarter of an hour. 



