350 Proceedings of Royal Society of Edinburgh. [july 4, 
(I wish, here, to thank my husband [Dr Griffiths] for the above 
determinations.) 
Then, again, on the addition of an alcoholic solution of silver 
nitrate to the purified oil, a white precipitate is thrown down. 
This precipitate, when allowed to crystallise from hot alcohol, 
separates in white needle-shaped crystals (fig. 2), as observed by 
low power under the micro- 
scope. This crystalline pre- 
cipitate is no doubt the 
silver nitrate compound of 
allyl sulphide, 
(C 3 B 5 ) 3 S ( AgNO s ) j 
gj The bulbs, peduncles, and 
leaves of this degenerated 
form of Tulip a sylvestris all 
yielded the same essential 
oil as above. No oil of 
mustard was detected in the 
above distillate as is usual 
(according to Dr Pless, Ann. 
Cliem. Pharm ., vol. lviii. 
p. 36) during the distillation of some plants containing either of 
the two isomeric oils of garlic and onion. 
Fig. 2. 
-Needle-shaped crystals of 
(C 3 H 5 ) 2 S(AgN0 3 ) 2 ” 
It is well known that many species of Allium yield, on distilla- 
tion, allyl sulphide ; also several genera of the Cruciferae yield the 
same chemical compound under similar treatment. Amongst these, 
Iberis amain, Alliaria officinalis, Tldaspi arvense (Wertlieim, Ann. 
Chem. Pliarm., vol. li. p. 289, and vol. liv. p. 297). But the 
essential oil, which is capable of yielding allyl sulphide, has not 
been found in the genus Tulipa, although it, like Allium, belongs to 
the Liliaceae. 
It has been shown by Professor Alphonse de Candolle ( Origin of 
Cultivated, Plants, p. 66) that the onion ( Allium cepa) is a very old 
form of the vegetable kingdom. He says : — “ Its [onion] cultiva- 
tion in Southern Asia and eastern region of the Mediterranean dates 
from a very early epoch.” Therefore, if the cultivated onion is a 
very ancient variety, what must be the age of its wild ancestor ? 
From the facts detailed in this paper, is it not likely that the wild 
