II Pitcher Plants 29 



For Hooker the tendril is a simple prolongation of the 

 leaf such as we see in various leaves, e.g. the lily-climber 

 Gloriosa, while he describes the development of the pitcher 

 as a simple dimpling and deepening of the upper surface 

 near the extreme tip of the tendril, which survives as the 

 mere rudiment already mentioned. He explains this 

 strange development as finding its possible initial rudiment 

 in those water-secreting glands common at the tip of so 

 many leaves, an apparatus which the reader may see at 

 work in the drop which often hangs at the leaf tip of his 

 white " Lily of the Nile" {Richardia africand) ; still better, 

 in many greenhouse arums ; or, best of all, on the dew- 

 gemmed leaves of Lady's Mantle {Alchemilla vulgaris) in a 

 summer morning's walk. Applying our histological experi- 

 ence, too, we may prepare excellent microscopic specimens 

 of these water glands from the leaf tips of Saxifrages or of 

 Indian Cress {TropcEoluvi) by carefully scraping away the 

 lower epidermis and parenchyma upon a glass slide in a 

 drop of water, and then turning over the remaining epi- 

 dermis to show its upper surface. 



Partly from his study of the pitcher leaves of seedling 

 Nepenthes, which appear immediately after the cotyledons, 

 and in which the pitcher seemed to him to develop from 

 the first as a much more important portion of the leaf, 

 Dickson was led to give up this doctrine of Hooker's. The 

 curiously "interrupted" leaves of some Crotons (C inter- 

 ruptus)., in which the flat portion, the intervening midrib, 

 and even the pitcher in a rudimentary form, are all present, 

 the latter as simply the upper third of the leaf, seemed to 

 him to afford the key to the difficulty ; the detailed develop- 

 ment of the pitcher as a leaf pouching seeming to him 

 essentially similar to that of Cephalotus, above mentioned. 

 Dr. Macfarlane's conclusions as to the nature of the pitchers 

 are very different. He believes that in Nepenthes, Heliam- 



