CAN THE LEAVES OF DEOSERA EAT FLESH ? §5 



CAT^ THE LEAVES OF DROSERA EAT FLESH? 



By 0. NoEDSTEDT. 



In recent years several authors have asserted that the leaves of 

 Drosera really consume the insects that settle upon and are imprisoned 

 by them, and farther that they are able to digest meat. 



E. Warming has described (Yidensk. Medd. fra den naturhis- 

 toriske Forening i Kjobenhavn, jN"©. 10 — 12, 1872,) the development 

 and real structure of the glands on the leaves of Brosera, but he has 

 not in detail examined the sticky mucus and its relation to the diges- 

 tion of meat. 



If the fully developed mucus of the glands be examined without che- 

 mical reagents, or merely treated with water, it seems to have no distinct 

 double-contoured external limit nor any coverings ; it is transparent, 

 uncoloured and homogeneous ; sometimes, however, there may be seen 

 some small ruund or staff-shaped apparently harder corpuscles at dif- 

 ferent points of the outermost delicate cellular membrane. Treated 

 with absolute alcohol the mucus contracts suddenly and considerably 

 (c. 95 per cent.) and then appears like a tissue of delicate cells, the 

 external limit of the mucus and the boundaries between its different 

 cells are now clearly to be seen. Usually the mucus contracts so much 

 that it bursts in the top of the gland and stands a little out from its 

 sides but is still fixed to the stalk, the upper half of which also often 

 secretes mucus. The best method of studying the successive contrac- 

 tion and swelling of the substance is to use Tinctura Alcannae, let 

 it dry slowly, and then alternately treat it with water and al- 

 cohol. Alcohol alone makes the contraction a little too rapid to be 

 observed in detail, and water alone, even the water that is in concen- 

 trated spirit, causes the intumescence to take place as rapidly. 

 Chloride of zinc colours the mucus pale yellow. Carmine diluted in 

 ammonia colours it transparent red ; a solution of aniline gives no 

 colour, or a very slight one. With iodine and sulphuric acid it be- 

 comes reddish-yellow and is then dissolved. Hydrate of potash turns 

 it yellow, then granular, and finally turbid, with the exception of 

 the yellowish granules. 



The mucus on the glands of Drosera seems then to be analogous 

 to the slime resulting from change of the external parts of cellular mem- 

 branes in some Algse, and is not a secretion from the cells. 



When the gland is deprived of its mucus the red colour of its cells 

 changes into violet or blue-green, and at last the cells become totally 

 discoloured ; almost the same change takes place when they are 

 treated with an alkali, ammonia, or hydrate of potash, which provea 

 that the colouring matter is Erythrophyll. Whether the mucus be 

 removed or an alkali be used, the hair will bend itself, the bending 

 principally taking place in the lower part of its stalk. The contents 

 of the cells of the stalk may remain totally unchanged when it be- 

 comes bent, but if the chemical action be stronger the change of 

 colour will progress from cell to cell through the whole length of the 

 stalk, and the contents will become granular or contract into lumps of 

 different size. It appears that these chemical reagents are not not able 



