Cuapr. VIL] DIGESTION. 71 
CHAPTER VI. 
THE DiGEstIVE Power OF THE SECRETION OF DrosEna. 
The secretion rendered acid by the direct and indirect excitement of the 
glands—Nature of the acid—Digestible substances—Albumen, its diges- 
tion arrested by alkalies, recommences by the addition of an acid—Meat 
—Fibrin—Syntonin—Areolar tissue—Cartilage — Fibro-cartilage — Bone 
—Enamel and dentine—Phosphate of lime—Fibrous basis’ of bone— 
Gelatine—Chondrin —Milk, casein and cheese—Gluten—Legumin-—Pollen 
—Globulin—Hematin—Indigestible substances — Epidermic productions 
—Fibro-elastic tissue—Mucin—Pepsin—Urea—Chitinc—Cellulose—Gun- 
eotton—Chlorophyll—Fat and oil—Starch—Action of the secretion on 
living seeds—Summary and concluding remarks. 
As we have seen that nitrogenous fluids act very differ- 
ently on the leaves of Drosera from non-nitrogenous fluids, 
and as the leaves remain clasped for a much longer time 
over various organic, bodies than over inorganic bodies, such 
as bits of glass, cinder, wood, c&c., it becomes an interesting 
inquiry, whether they can only absorb matter already in 
solution, or, render it soluble,—that is, have the power of 
digestion. We shall immediately sce that they certainly have 
this power, and that, they. act on albuminous compounds in 
exactly the same manner as does the gastric juice of mam- 
mals; the digested matter being afterwards absorbed. This 
fact, which will be clearly proved, is a wonderful one in the 
physiology, of plants. I must here state that I have been 
aided throughout all my later,experiments by many valuable 
suggestions and assistance given me with the greatest kind- 
ness by Dr. Burdon, Sanderson. 
- It may be well to premise for the sake of any reader who 
knows nothing: about the digestion of albuminous compounds 
by animals that this is effected by means ofa ferment, 
pepsin, together with weak hydrochloric acid, though almost 
any acid, will serve., Yet neither pepsin: nor an acid by 
itself has any such power.* We have scen that when the 
‘* It appears, however, according a very minute quantity of coagulated 
to Schiff, and contrary to the opinion albumen. Schiff, “Phys. de la Di- 
of some physiologists, that weak hy- gestion,’ 1867, tom. ii. p. 25. 
drochloric dissolves, though slowly, : 
