THE PHYSIOLOGY OF PITCHER-PLANTS. 



97 



the Sarracenia, which make a pretty appearance with their 

 mouths open to catch the rains and dews ; but many poor insects 

 lose their lives by being drowned in these cisterns of water." It 

 should also be mentioned that Bobart (in Morison, " Plant. Hist. 

 Oxon.," hi., p. 533, 1699) had suggested that the aperture of the 

 pitcher was opened and closed from time to time by the change in 

 position of the lid, or rather the hood, working as it were on a 

 hinge. Of Coilophyllum virginianum breviore folio, he says : — 

 " In suprema folii parte labrum latum subrotundum est . . . 

 operculi vicem praestans, cardinis motu donatum, quo os 

 cavitatis frequenter contegitur ; " and of another species (longiore 

 folio erecto) : — "In summo uniuscuj usque ad unum latus, labrum 

 tegumentumve prominens enascitur, quod in his speciebus 

 operculum est, quod divina providentia ad obtegendam et 

 defendendam plan tarn a pluviarum injuriis statutum videtur, et 

 theculam scloppeti aut vasis lignei operimentum baud inepte 

 refert." Linnaeus at one time adopted the view of the 

 mobility of the lid, for we find him saying, in his " Hortus ClifTor- 

 tianus" (1737, p. 497) : — " Folia harum uti nepenthes folia folli- 

 culo constant, qui operculo, cardinis motu quasi donato, claudi 

 potest et aperiri." 



An important step onwards was made by Sir J. E. Smith, 

 early in the present century. In his "Introduction to Physiological 

 and Systematic Botany" (I quote from the 2nd Edn., 1809, p. 

 195), after giving Linnaaus' view of the use of the pitchers as 

 reservoirs of water, he goes on to say : — " But the consideration 

 of some other species renders this hypothesis very doubtful. 

 Sarracenia flava and S. adunca are so constructed that rain is 

 nearly excluded from the hollow of their leaves, and yet that part 

 contains water which seems to be secreted by the base of each 

 leaf. What then is the purpose of this unusual contrivance? " 

 He then alludes to the constant presence of dead insects in the 

 pitchers in these terms : — " The S. purpurea is usually observed to 

 be stored with putrefying insects, whose scent is perceptible as we 

 pass the plant in a garden ; for the margin of its leaves is beset 

 with inverted hairs, which, like the wires of a mouse-trap, render 

 it very difficult for any unfortunate fly that has fallen into the 

 watery tube, to crawl out again. Probably the air evolved by 

 these dead flies may be beneficial to vegetation, and, as far as the 

 plant is concerned, its curious construction may be designed to 



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