58 Chapters in Modern Botany CHAP. 



has grown up, one may practically say entirely, since 

 Hooker and Darwin, Tait, and others carried out the 

 experiments upon which current ideas became established. 

 Without denying then the existence of traces of digestive 

 ferment, such as may be prepared from all or almost all 

 living protoplasm, be it of a seed, a fungus, or a morsel 

 of muscle, he affirms that when the fluid of a pitcher is 

 sterilised so as to exclude the action of bacteria, no diges- 

 tion takes place in short, for him such digestion and dis- 

 solution of the bodies of insects or artificially supplied food 

 material is simply the work of bacteria, and so comes 

 into line not with digestion, but with putrefaction and 

 decay. He even extends this to fly-traps and sundews. 



Need of Further Investigation ; Possible Compromise. 

 It may seem at first sight as if we were but returning to 

 the position of the ancients, yet from either side of the dis- 

 pute it is easy to correct that impression. Even if our Dar- 

 winism be vain, a new explanation has come in sight that 

 associated with transpiration and has to be applied in turn. 

 For if pitchers be reservoirs, how do they operate? How 

 shall we explain the glutinous and deliquescent " azerin "- 

 say, as impeding evaporation, or even itself at times helping 

 to draw water from the atmosphere, as the aerial roots do for 

 an orchid? Or does it act, say on sundews, by aiding the 

 transpiratory current, so necessary to the ordinary processes 

 of vegetative life and growth by compelling an exosmose of 

 water to dilute it? Here, then, a new and as yet practi- 

 cally untried field of experiment opens out before us. In 

 fact, despite Darwin's volume, the whole subject of tran- 

 spiration in sundews and other insectivorous plants, notably 

 of course Nepenthes, has still to be experimentally investi- 

 gated by the vegetable physiologist, before the function of 

 pitchers or tenacles can be really understood. Yet our 

 Darwinian interpretations will not be so easily dismissed, 



