244 



DION-a:A MUSCIPULA. 



[Chap. XIII. 



are studded. From facts hereafter to be given in the chap- 

 ters on Aldrovanda and Utricularia, it seemed probable that 

 they served to absorb decayed matter left by the captured in- 

 sects; but their position on the backs of the leaves and on 

 the footstalks rendered this almost impossible. Neverthe- 

 less, leaves were immersed in a solution of one part of urea 

 to 437 of water, and after 24 hrs. the orange layer of proto- 

 plasm within the arms of these processes did not appear more 

 aggregated than in other specimens kept in water. I then 

 tried suspending a leaf in a bottle over an excessively putrid 

 infusion of raw meat, to see whether they absorbed the va- 

 pour, but their contents were not affected. 



Digestive Power of the Secretion." When a leaf closes 

 over any object, it may be said to form itself into a tempo- 

 rary stomach; and if the object yields ever so little animal 



'Dr. W. M. Cnnby, of Wll- 

 mln^oD, to whom I nin much in- 

 dobtpd for Information rppirding 

 I)lonn>n In Its native home, has 



aiibUHhed In the ' Gardener's 

 [onthly.' Philadelphia, August, 

 18(W, 8ome Interesting observa- 

 tions. He ascertained that the 

 secretion digests animal matter, 

 such as the contents of Insects, 

 bits of meat, &c.; and that the 

 secretion Is reabsorbed. He was 

 also well aware that the lobes 

 remain closed for a much longer 

 time when In contact with animal 

 matter than when made to shut 

 by a mere touch, or over objects 

 not yielding soluble nutriment; 

 and that In thewe latter cases the 



f lands do not secrete. The Kev. 

 >r. f'urtis first observed (' Bos- 

 ton Journal Nat. Hist.' vol. i. p. 

 12.1) the secretion from the 

 glands. I may here add that a 

 gardener. Mr. Knight, Is said 

 {KIrby and Spenoe's ' Introduc- 

 tion to Entomology,' 1818, vol. I. 

 p. 205) to have found that a 



ftlant of the I)lona?a, on the 

 eaves of which " he laid fine fila- 

 ments of raw beef, was much 

 more luxuriant in its growth 

 than others not so treated." 



[The earlier history of the 

 siil)Je<'t is given in Sir Josnh 

 Hooljer's " Address to the De- 

 partment of Hot any and Zoolo- 

 gy." Hrltlsh AKSoolatlon Ue- 

 port,' 1874, p. lf2, whence the 

 following facts are taken. 



Aliout 1708 Ellis, a well known 

 Rncllsh naturalist, sent to Iiln- 

 lupus a drawing and specimens of 



Dlonsea with the following re- 

 marks ("A Itotnnlcal DeHcrtptioii 

 of the Dion<rn muMcipula .... In 

 a letter to Sir Charles Linnseus," 

 p. 37):- 



" The plant, of which I now 

 enclose you an exact figure .... 

 shows that Nature may have 

 8om views towards its nourish- 

 ment. In forming the upper Joint 

 of its leaf like a machine to catch 

 food." 



Llnnneus was unable to believe 

 that the plant could profit by the 

 captured Insects; he only saw in 

 the phenomena " an extreme case 

 of sensitiveness in the leaves 

 which causes them to fold up 

 where Irritated, Just as the sensi- 

 tive plant does; and he conse- 

 quentlv reganled the capture of 

 the disturbing insect as some- 

 thing merely accidental and of 

 no importance to the plant. . . . 

 LJnnHMis's authority overbore 

 criticism If any was offered; and 

 his statement alMxit the behav- 

 iour of the leaves was copied 

 from book to book. . . . Dr. 

 [Erasmus] Darwin (1791) was 

 contented to suppose that Dlomea 

 surrounded Itself with Insect- 

 traps to prevent depredations 

 upon its flowers. Dr. Curtis, 

 whose ct)ntrlbutl(>n to the subject 

 has been alreaiiy mentioned, de- 

 scribes the capturefl Insects na 

 envelopefl In a fluid of a mucilag- 

 inous consistence which seems to 

 act as a solvent, the Insects be- 

 ing more or less consumed by it." 

 -F. D.] 



