SPONTANEOUS MOVEMENTS IN PLANTS. 
831 
contains even more complete and accurate information than any 
preceding one. As a work of reference it should be on the shelves 
of all, as being indispensable to those especially who have any con¬ 
nection with medicine, or the manufacture connected therewith. 
Extracts from British and Foreign Journals. 
SPONTANEOUS MOVEMENTS IN PLANTS. 
By Alfred W. Bennett, M.A., B.Sc., E.L.S. 
That there are no “ hard and fast lines” in Nature is a 
truth which is more and more forcing itself upon the minds 
of men of science. The older naturalists delighted to circum¬ 
scribe their own special domains within sharply marked boun¬ 
daries, which no trespassers were allowed to pass. We have 
long given up the attempt thus accurately to map out the 
kingdom of Nature. Her varied productions are connected 
with one another by innumerable links and cross-links; and 
our systems of classification, even the most “ natural,” are 
but an imperfect human contrivance for bringing together 
those forms which present the most evident marks of resem¬ 
blance or affinity. While the truth of this law is most familiar 
in the case of those smaller subdivisions of the animal and 
vegetable kingdoms—classes, orders, and genera—which are 
connected with one another by innumerable intermediate 
forms, it is none the less certain in the line of demarcation 
which separates these two great kingdoms themselves from 
one another. In attempting to draw up a definition which 
shall serve accurately and infallibly to distinguish between 
the animal and vegetable kingdoms, we find ourselves com¬ 
pelled to abandon one supposed crucial test after another, 
and to content ourselves at last with framing, as in the case 
of the lower subdivisions, an assemblage of characters, by the 
tout ensemble of which we must decide whether our organism 
is an animal or a plant. So great is the uncertainty as to the 
actual boundary-line, that large groups of lowly organisms, 
such as those known as Diatoms and Desmideae, have been 
regarded by experienced authorities as belonging to each 
kingdom ; and one of the ablest of living naturalists, Ernst 
Haeckel of Jena, has proposed the division of the material 
xl v. 56 
