Cuar. VI] DIGESTION. 105 
Radish seeds (Raphanus 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 (Lepidium sativum) of the previous year were placed on 
four leaves; two of these inext morning were moderately and two 
strongly inflected, and remained so for four, five, and even six days. 
Soon after these sceds were placed on the leaves 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 
of 3 hrs., and were still closely inflected on the third day; so that it 
evidently was not the mucus which excited so much inflection; on the 
contrary, this served to a certain extent as a protection to the sees. 
Two of the six seeds germinated whilst still lying on the leaves, but 
the seedlings, when transferred to damp sand, soon died; of the other 
four seeds, only one germinated. 
Two seeds of mustard (Sinapis nigra), two of celery (Apium grave- 
olens)—both of the previous year, two seeds well soaked of caraway 
(Carum carui), and two of wheat, did not excite the leaves more than 
inorganic objects often do. Five seeds, hardly ripe, of a buttercup 
(Ranunculus), and two fresh seeds of Anemone nemorosd, induced 
only a little more effect. On the other hand, four seeds, perhaps not 
quite ripe, of Carex sylvatica caused the leaves on which they weie 
placed to be very strongly inflected; and these only began to re-expand 
on the third day, one remaining inflected for seven days. 
It follows from these few facts that different kinas of seeds excite 
the leaves in very different degrees; whether this is solely due to the 
nature of their coats is not clear. ln the case of the cress seeds, the 
partial removal of the layer of mucus hastened the inflection of the 
tentacles. Whenever the leaves remain inflected during several days 
over seeds, it is clear that they absorb some matter from them. That 
the secretion penetrates their coats is also evident from the large pro- 
portion of cabbage, raddish, and cress seeds which were killed, ande 
from several of the seedlings being greatly injured. This injury to 
the seeds and seedlings may, however, be due solely to the acid of the 
secretion, and not to any process of digestion; for Mr. Traherne 
Moggridge has shown that very weak acids of the acetic series are 
highly injurious to seeds. It never occurred to me to observe whether 
seeds are often blown on to the viscid leaves of plants growing 1n @ 
state of nature; but this can hardly fail sometimes to occur, as we 
shall hereafter see in the case of Pinguicula. If so, Drosera will profit 
to a slight degree by absorbing matter from such seeds, 
