I Pitcher Plants 19 



astonishing to me until I knew the peculiar properties of 

 azerin. In the process of digestion this penetration of the 

 fluid must also be usefuh'' 



Secreting Glands as Nectaries. — So far we have been 

 looking at the glands of the Nepenthes pitcher as peculiar 

 organs special to their position ; but soon after the re- 

 examination of the pitcher by Professor Dickson, which 

 resulted in the discovery of those curious marginal glands 

 (which we may view as the highest specialisation of the 

 gland structures of the lid and pitcher — perhaps, indeed, of 

 the secreting gland yet known in the vegetable kingdom), 

 Dr. Macfarlane made an interesting step towards the 

 determination of the less specialised organ to which the 

 whole of these peculiar structures may be referred, and of 

 which they may be considered developments and modifica- 

 tions. Closely examining the whole plant, he noticed that 

 " not only is honey secreted by the inside of the lid and 

 the mouth of the pitcher, as we already knew, but the 

 outer surface of the pitcher, as well as that of the lid, also 

 possesses honey glands. Further, the whole so-called 

 ' leaf,' or expanded lamina, including the thong-like pro- 

 longation of the midrib, to the end of which the pitcher 

 is attached, may be regarded as a complete insect-lure, 

 seeing it also is found to be studded with honey-secreting 

 glands, thus presenting to unwary insects a long but 

 pleasant passage to the cavity of the pitcher below. The 

 stem, too, was found to possess glands for honey secretion 

 — in some species to a greater extent than in others." 

 The curator of the Edinburgh Botanic Garden drew Dr. 

 Macfarlane's attention to the viscid nature of the fluid 

 secreted by Nepenthes when flowering, and it was found 

 that this also was a honey secretion, and glands were dis- 

 covered to be present on the upper epidermis of the 

 sepals. Dr. Macfarlane then made a minute examination 



