Chap. VI.] DIGESTION. 77 



head albumen, showing that the secretion loses its power 

 when neutralised by an alkali, and recovers it when an acid 

 is added. 



Substances which are completely or partially Digested hy the 

 Secretion of Drosera. 



Albumen. After having tried various substances, Dr. 

 Burdon Sanderson suggested to me the use of cubes of coagu- 

 lated albumen or hard-boiled egg. I may premise that five 

 cubes of the same size as those used in the following experi- 

 ments were placed for the sake of comparison at the same 

 time on wet moss close to the plants of Drosera. The 

 weather was hot, and after four days some of the cubes were 

 discoloured and mouldy, with their angles a little rounded; 

 but they were not surrounded by a zone of transparent fluid 

 as in the case of those undergoing digestion. Other cubes 

 retained their angles and white colour. After eight days all 

 were somewhat reduced in size, discoloured, with their angles 

 much rounded. Nevertheless in four out of the five speci- 

 mens, the central parts were still white and opaque. So 

 that their state differed widely, as we shall see, from that of 

 the cubes subjected to the action of the secretion. 



Experiment 1. Eather large cubes of albumen were first tried; 

 the tentacles were well inflected in 24 hrs.; after an additional day 

 the angles of the cubes were dissolved and rounded ; * but the 

 cubes were too large, so that the leaves were injured, and arfter 

 seven days one died and the others were dying. Albumen which 

 has been kept for four or five days, and which, it may be pre- 

 sumed, has begim to decay slightly, seems to act more quickly 

 than freshly boiled eggs. As the latter were generally used, I often 

 moistened them with a little saliva, to make the tentacles close 

 more quickly. 



Experiment 2. A cube of tV of an inch (i. e. with each side -^ 

 of an inch, or 2.54 mm., in length) was placed on a leaf, and after 

 50 hrs. it was converted into a sphere about -^g of an inch 

 (1.905 mm.) in diameter, surrounded by perfectly transparent fluid. 

 After ten days the leaf re-expanded, but there was still left on 

 the disc a minute bit of albumen now rendered transparent. More 



* In all my numerous experl- Istlc of the dtgeRtlon of nibnmen 



ments on the digestion of cubes by the gnstrlc Juice of anIuiiilH. 



of albumen, the anjrles and t'<l.t?e8 On the other hand, ho roniarkH, 



were Invariably tlrst rounded. " les dlssolntlons, en chimb', ont 



Now, Schlff states (' Lof.-ons lieu sur toute la surface d8 



Phys. de la' Digestion,' 1807, toin. corps en contact avec Tugent Ul- 



il.. p. 140) that this is character- solvaut." 



