NOTES. 
GRAPE SUGAR AS AN EXCRETION IN PLATYCERIUM.—Nectarial 
tissues are by no means common among the Vascular Cryptogams, their presence 
having been only observed in the genera Cyathea , Hemitelia , Angiopteris , and 
Pier id him ; 1 their significance remains as yet obscure. 
Specimens of Platycerium grande in the Tropical Ferneries at Kew afford 
another instance of nectar-excretory tissues among the Ferns, where in the early hours 
of the morning (6-9 a.m.) the lower surfaces of the young barren fronds or ‘ mantle 
leaves ’ are copiously studded towards their tips with drops of liquid, which disappear 
later on in the day, and subsequently wholly at the maturation of the fronds. 
In Plalycerium alcicorne , the Stag’s-horn Fern, and P. biforme , these exudations 
occur to a lesser extent, and occasionally on the fertile fronds as well. 
Upper Epidermis 
t 
x Lower Epidermis n 
These drops have a sweetish taste, and on testing with Fehling’s solution yield 
the brick-red precipitate characteristic of grape sugar; the presence of ants in their 
neighbourhood primarily suggested the test. 
A microscopic examination of the lower surface of the ‘leaves’ reveals the 
existence of stellate hairs with pointed ray cells, and others similarly branched with 
obtuse ray cells, which latter appear glandular. Between these hairs, slight rounded 
elevations correlated with internal lacunae, which show no definite epithelial layer, but 
contain a liquid excretion presumably, are visible. 
Occasionally these lacunae are below the epithelial layers, but it sometimes 
happens that the epidermal cells are ruptured, when the lacunae are exposed (Figs. I 
1 Engler and Prantl: Pflanzenfamilien Filicales I, iv, 1899, p. 66. 
Annals of Botany, Vol. XXV. No. C. October, 1911.] 
4 K 
