SENSITIYE PLA^^TS. 
23 
braAch of the science he may study, stands abashed. Watch 
the passage of fluids from one cell to another ; nay more, strip 
off the outer coating of the cell — the cell-wall — and leave the 
little dab of slime, as it has somewhat contemptuously been 
called, and watch its sometimes active movements ; see it con- 
tract and expand, observe the chemical changes that take place 
in it. \Miere now is the difference between the animal and vege- 
table physiologist ? Is the one better able than the other to 
cry “ Eureka, this is the mystery ? ” Can the one float better 
than the other in the sea of knowledge, or are they not both 
equally at fault ? Nevertheless, the experience of the last few 
years has shown that the investigation of these humble cells 
and their doings is, in all probability, the one path by which the 
physiologist has to travel in order to unravel as much of the 
mysteries of life as it may ever be granted to man to solve. 
Motion among animals implies a muscular apparatus of some 
sort or other; it implies a sensibility to external impressions, 
and, at any rate in the higher groups, a greater or less degree of 
volition, and as a consequence a nervous system. In the case 
of plants, there is motion of various kinds ; there is evident 
se^nsibility to external impressions; and there is evidently a 
power of transmitting impressions from one part to another. 
But, so far as structure is concerned, there is no muscular 
system — no nervous system, at least in the sense in which those 
terms are usually employed. The lowest animals, those debate- 
able creatures concerning whose nationality such contests have 
been waged, are no better off. Where is their muscular system ? 
Where are their nerves ? And yet they move, they show a re- 
pugnance to noxious agents, they are evidently in a degree 
sensitive. Clearly then, the essential attributes of both muscular 
and sentient structure are to be sought among these humble 
organisms, plants or animals, it is indifferent in which division 
they are placed. And, as has been before said, there is no room 
for glorification on the part of one naturalist over another. 
Both are alike ignorant. Travelling by two different roads, 
they have come to the same point, picked up much information 
on the way ; so much that neither the one nor the other have the 
least doubt of accumulating a great deal more in due season. 
In the present article we hope to be able to present to the 
reader a sketch of what is known as to the movements ex- 
ercised by plants, and specially by those usually termed sen- 
sitive plants.” And here it may be remarked, that the actual 
movements exhibited by sensitive plants are not materially dif- 
ferent, except in degree, from those more general movements 
which, from being always under our eyes, attract less attention 
than they would were they only occasionally visible. F or instance, 
the elevation and depression of leaves according as they are 
