Cuar. XI. GENERAL SUMMARY. 269 
an alkali, which entirely arrested the process of diges- 
tion, this immediately recommencing as soon as the 
alkali was neutralised by a little weak hydrochloric 
acid. From trials made with a large number of 
substances, it was found that those which the secretion 
of Drosera dissolves completely, or partially, or not 
at all, are acted on in exactly the same manner by 
gastric juice. We may, therefore, conclude that the 
ferment of Drosera is closely analogous to, or identical 
with, the pepsin of animals. 
The substances which are digested by Drosera act 
on the leaves very differently. Some cause much 
more energetic and rapid inflection of the tentacles, 
and keep them inflected for a much longer time, than 
do others. We are thus led to believe that the 
former are more nutritious than the latter, as is 
known to be the case with some of these same sub- 
stances when given to animals; for instance, meat in 
comparison with gelatine. As cartilage is so tough a 
substance and is so little acted on by water, its 
prompt dissolution by the secretion of Drosera, and 
subsequent absorption, is, perhaps, one of the most 
striking cases. But it is not really more remarkable 
than the digestion of meat, which is dissolved by this 
secretion in the same manner and by the same stages 
as by gastric juice. The secretion dissolves bone, and 
even the enamel of teeth, but this is simply due to 
the large quantity of acid secreted, owing, apparently, 
to the desire of the plant for phosphorus. In the 
case of bone, the ferment does not come into play 
until all the phosphate of lime has been decomposed 
and free acid is present, and then the fibrous basis is 
quickly dissolved. Lastly, the secretion attacks and 
dissolves matter out of living seeds, which it some- 
times kills, or injures, as shown by the diseased state 
