XX PROCEEDINGS OF THE ROYAL HORTICULTURAL SOCIETY. 



of only one, and were thus enabled by their structure to offer a 

 greater degree of resistance to injurious vapours than plants less 

 well equipped. Dr. Masters also observed that plants with an 

 aqueous hypodermal layer, such as was present in certain Orchids, 

 might on that account be better able to resist the injurious 

 effects of fogs. Mr. Henslow added that E. I. Rhododendrons 

 have much tannin, a moderately thick cuticle, and aqueous 

 layers on both sides of their leaves, and as they withstood the 

 fogs well these features might corroborate Dr. Masters's sugges- 

 tion. Dr. Masters also remarked on the observation of Prof. 

 Oliver that Monocotyledons appeared to be less liable to injury 

 than Dicotyledons. He threw out the suggestion that as so 

 many of the former class have a more or less erect phyllodinous 

 foliage, the fog deposit would be less likely to accumulate upon 

 it than on the more usually horizontal blades of dicotyledonous 

 plants. In addition to this morphological feature was the 

 anatomical structure — viz. there being two palisade layers and 

 the presence of stomata on both sides, Sec. Such and other 

 histological differences, though apparently not borne out in the 

 case of Ferns, might account for some of the differences 

 mentioned. 



The thanks of the Committee were unanimously tendered to 

 Prof. Oliver for his interesting and valuable report. (See page 1.) 



Scientific Committee, March 28, 1893. 



Dr. Hugo Muller in the Chair, and five members present. 



The Antiquity of the Citron in Egypt. — A communication 

 was received from Dr. Bonavia, in which he referred to M. V. 

 Loret's paper on this subject, entitled 14 Le Cedratier dans 

 l'Antiquite " (Paris, 1891). The author mentions several writers 

 from 2 b.c. to 3G0 a.d., and states that it was cultivated in the 

 fourth century a.d. in Upper Egypt (Coptic, " Glritre "), while a 

 Citron is said to have been found in a tomb of the 12th century 

 b.c. It is also figured on the temple of Thothmes III. at 

 Karnak, 15th century b.c. From a drawing it would seem that 

 even the "fingered Citron" might have been known. Dr. 

 Bonavia discusses the probable source of the Citron in Egypt as 

 being brought by traders through the Persian Gulf and Red Sea, 



