Cuapr. VIL DIGESTION. 127 
and we know that leaves immersed in an emulsion of starch 
are not at all affected. I need hardly say that starch is not 
digested by the gastric juice of animals. 
Action of the Secretion on Living Seeds. 
The results of some experiments on living seeds, selected by 
hazard, may here be given, though they bear only indirectly on 
our present subject of digestion. 
Seven cabbage seeds of the previous year were placed on the 
same number of leaves. Some of these leaves were moderately, 
but the greater number only slightly inflected, and most of 
them re-expanded on the third day. One, however, remained 
clasped till the fourth, and another till the fifth day. These 
leaves therefore were excited somewhat more by the seeds than 
by inorganic objects of the same size. After they re-expanded, 
the seeds were placed under favourable conditions on damp 
sand; other seeds of the same lot being tried at the same time 
in the same manner, and found to germinate well. Of the seven 
seeds which had been exposed to the secretion, only three ger- 
minated; and one of the three seedlings soon perished, the tip 
of its radicle being from the first decayed, and the edges of 
its cotyledons of a dark brown colour; so that altogether five 
out of the seven seeds ultimately perished. 
Radish seeds (Laphanus sativus) of the previous year were 
placed on three leaves, which became moderately inflected, and 
re-expanded on the third or fourth day. Two of these seeds 
were transferred to damp sand; only one germinated, and that 
very slowly. This seedling had an extremely short, crooked, 
diseased, radicle, with no absorbent hairs; and the cotyledons 
were oddly mottled with purple, with the edges blackened and 
partly withered. 
Cress seeds (Lepidum sativum) of the previous year were 
placed on four leaves; two of these next morning were mode- 
rately and two strongly inflected, and remained so for four, 
five, and even six days. Soon after these seeds were placed on 
the Ieaves and had become damp, they secreted in the usual 
manner a layer of tenacious mucus; and to ascertain whether 
it was the absorption of this substance by the glands which 
caused so much inflection, two seeds were put into water, and 
as much of the mucus as possible scraped off. They were then 
placed on leaves, which became very strongly inflected in the 
course ot 3 hrs., and were still closely inflected on the third 
day ; so that it evidently was not the mucus which excited so 
