Mr Parkin, On a reserve carbohydrate, etc. 139 



On a reserve carbohydrate, which produces mannose, from the 

 bulb of Lilium. By J. Parkin, M.A., Trinity College. 



[Bead 4 March 1901.] 



Besides starch the bulbs of members of the genus Lilium 

 contain another reserve carbohydrate. It exists as a sort of 

 mucilage in the cell-sap of all the parenchymatous cells of the 

 bulb-scales. Alcohol precipitates and hardens it, so that sections 

 of scales preserved in spirit show each cell filled with a solid block 

 of mucilage, in which the starch grains are embedded. On treat- 

 ment with water the mucilage swells and gradually dissolves, 

 liberating the starch grains. Thus the alcoholic material presents 

 somewhat the same microscopic appearance as that of other 

 monocotyledonous reserve organs containing starch and inulin, for 

 example the Hyacinth bulb described in a former paper 1 . Lilium, 

 however, did not respond to the microchemical tests used there, 

 and so these bulbs were merely referred to as possessing starch 

 and not inulin. 



In some recent papers by Leclerc du Sablon 2 on reserves of 

 bulbs and tubers, he speaks of the carbohydrate soluble in water 

 but insoluble in strong alcohol as dextrin. No conclusive evidence 

 is given to prove that it is such. He seems merely to have found 

 that it is readily hydrolysed by an acid to produce sugar reducing 

 Fehling's solution. The monocotyledons he mentions more par- 

 ticularly as possessing dextrin in their reserve organs are Lilium 

 candidum, Hyacinthus orientalis, Tidipa Gesneriana and Ophr'ys 

 aranifera. 



Proof has previously been given 3 that his supposed dextrin in 

 the Hyacinth bulb is inulin, or at any rate a carbohydrate 

 producing fructose (levulose) on hydrolysis. 



The carbohydrate occurring along with starch in the bulb of 

 Lilium candidum has now been chemically examined, and found 

 to be one yielding mannose and not glucose on hydrolysis. 



Chemical examination. The bulbs used were taken from the 

 ground on September 20th, at a time when the foliage was 

 withering. The scales were removed, cleaned, sliced in pieces and 

 allowed to dry at the ordinary temperature in a current of air 

 They were then ground up. 



About 17 grams of this dried material were taken and 



1 Parkin, Phil. Trans. Roy. Soc. Ijond., ser. B, vol. cxci. (1899), pp. 61 — 64. 



2 Leclerc du Sablon, Rev. Gen. de Bot., 1898. 



3 Parkin, Annals of Botany, vol. xiv. 1900, pp. 155 — 157. 



