CARNIVOROUS PLANTS WITH ADHESIVE APPARATUS. 157 



with the nitrogenous compounds dissolved therein, is absorbed without delay. 

 Hollows of this kind occurring in foliage-leaves only differ from those above 

 described as developed on sarracenias in being destitute of special contrivances for 

 decoying animals into the traps, and for rendering their escape from the latter 

 impossible. It cannot be denied that through forms of this kind a gradual 

 transition has been proved to exist between plants which absorb nearly pure water 

 by means of their foliage-leaves and those which capture animals. And, further, 

 amongst the latter we find all graaations ol mecnanism from Brosojohylluvi and 

 the Primulas with their epiphyllous secretory glands up to the Fly-trap (Bioncea), 

 which exhibits the most complex apparatus of all for capturing and digesting prey, 

 and in which division of labour is carried to its highest development by the com- 

 munities of cells constituting the foliage-leaves. 



It is not surprising that the first apparatus for capturing and digesting insects 

 to be noticed, to have its functions recognized and to be described, was that of 

 Dioncea. But it strikes one as all the more strange that of late the question has 

 repeatedly been mooted in the very case of Dioncea, as to whether the capture and 

 digestion of insects is not injurious instead of beneficial to these plants. Gardeners, 

 who have cultivated Dioncea in greenhouses, have made the observation that 

 individuals protected from the visits of insects thrived at least as well as those 

 whose leaves were covered with bits of meat, &c., or, to employ the usual phrase, 

 were fed with meat. It has also been found that a leaf cannot stand more than 

 three meals; indeed, it often happens that even after the first occasion of digesting 

 a bit of meat, the leaf concerned shows signs of having been injured by the 

 repast. That is to say, a long time elapses before leaves which have digested 

 a largish albuminoid mass regain their normal irritability; and often they wither 

 and die. If cheese is placed on Dioncea, it is true the leaf closes over it, and there 

 is a commencement of the process of solution, but before this is accomplished the 

 leaf turns brown and perishes. Yet if Dioncea were obliged to lose a leaf after 

 every meal, the result would be very disadvantageous. 



As against these considerations, we have first of all to remark that the 

 absorption of nutriment takes place in nature in a manner diflfering materially from 

 the phenomenon in greenhouses. A leaf of Dioncea in the wild state is protected 

 against the possibility of receiving too plentiful a dose of albuminoid substances at 

 a time. Insects so large as not to allow the lobes to close together over them slip 

 out again, and only small ones are caught and retained. When, in the latter case, 

 one deducts the chitinous coat, and m general all parts not susceptible of being 

 digested, such a small quantity of albuminoid compounds is left that, compared with 

 it, the little cubes of meat used in the experiments made in greenhouses must be 

 looked upon as an exceedingly sumptuous repast. But that so small an amount of 

 nitrogenous food as is to be derived from a tiny captured insect does not act 

 injuriously, follows from the fact that dionaeas growing wild flourish excellently, 

 and do not exhibit the brown discoloration of the leaves which is caused in a 

 greenhouse by placing bits of cheese upon them. If the absorption of nitrogenous 



