Cuar. VIJ DIGESTION. 79 
for, after 48 hrs., the cubes were completely dissulved on all three 
leaves. On the third day the leaves began to re-expand, and on tlie 
fourth day all the fluid was absorbed.” 
_Keperiment 7.—Small cubes of albumen were put on two leaves, 
and minute drops of hydrochloric acid, of the strength of one part to 
487 of water, were added two or three times. This did not in the 
least delay, but seemed rather to hasten, the process of digestion ; 
for every trace of the albumen disappeared in 24 hrs. 80 m. After 
three days-the leaves partially re-expanded, and by this time almost 
all the. viscid fluid on their discs was absorbed. It is almost super- 
‘ fluous to state that cubes of albumen of the same size as those above 
used, left for seven days in a little hydrochloric acid of the above 
strength, retained all their angles as perfect as ever. 
Experiment 8.—Cubes of albumen (of 5 of. an inch, or 1°27 mm.) 
were-placed on’ five leaves, and minute drops of a solution of one part 
of carbonate of soda to 487-of water were added at intervals to three 
of them, and drops of carbonate of potash, of the same strength to the 
other two. ‘The drops were given on the head of a rather large pin, 
and I ascertained that each was equal to about 75 of a minim (-0059 
c.¢.), 80 that, each contained only z)5— of a grain (*0135-mg.) of: the 
‘alkali. This was not sufficient, for after 46 hrs. all five cubes were 
‘dissolved. ‘ 
Laperiment 9.—The last experiment was repeated on four leaves, 
with this difference, that. drops of the same solution of carbonate of 
‘soda were added rather oftener, as often as the secretion became acid, 
.so that it was much more effectually neutralised. And now after 24 
hrs. the angles of three of the cubes were not in the least rounded, 
those of the fourth being so in a very. slight degree. Drops of 
extremely weak hydrochloric acid (viz. one part to 847 of water) were 
‘then added, just enough to neutralise the alkali which was still present ; 
and now digestion immediately recommenced, so. that after 28 hrs. 
80 m. three of the cubes were completely dissolved, whilst the fourth 
was converted into a minute sphere, surrounded by transparent fluid’; 
and this sphere next day disappeared. } 
Experiment 10.—Stronger solutions of carbonate of soda and of 
potash were next used, viz. one part to 109 of water ; and as the same- 
sized drops were given as before, each drop contained yJ55 of a grain 
(0539 mg.) of either salt. Two cubes of albumen (each about 75 of 
an inch, or *635 mm.) were placed on the same leaf, and two on another. 
Each leaf received, as soon as the secretion became slightly acid (and 
this occurred four times within 24 hrs.), drops either of the soda or 
potash, and the acid was thus effectually neutralised. ‘lhe experiment 
now succeeded perfectly, for after 22 hrs. the angles of the cubes were 
as sharp as they were at first, and we know from experiment 5 that 
such small cubes would have been completely rounded within this time 
by the secretion in its natural state. Some of the fluid was now 
removed with blotting-paper from the discs of the leaves, and minute 
drops of hydrochloric acid of the strength of one part to 200 of water 
