182 FOUNDATIONS OF BOTANY 
with nitrogen to meke various proteid compounds, either 
for immediate use or for reserve food. Many other com- 
plicated transformations occur. 
(3) The power to cast off waste or used-up- material 
(excretion). Getting rid of surplus water (Sect. 174) and 
of oxygen (Sect. 178) constitutes a very large part of the 
excretory work of plants. 
(4) The capacity for growth and the production of off- 
spring (reproduction). ‘These are especially characteristic 
of living protoplasm. It is true that non-living objects 
may grow in a certain sense, as an icicle or a crystal of 
salt or of alum in a solution of its own material does. 
But growth by the process of taking suitable particles 
into the interior of the growing substance and arranging 
them into an orderly structure (Fig. 126) is possible only 
in the case of live protoplasm. 
(5) The possession of the power of originating move- 
ments not wholly and directly caused by any external 
impulse (automatic movements). Such, for instance, are 
the lashing movements of the cilia of the swarmspores 
of slime moulds, or the slow pendulum movements of 
Oscillatoria (Sect. 269), or the slow vibrating movements 
of the stipules of the “telegraph plant” (Desmodium), 
not uncommon in greenhouses. 
(6) The power of shrinking or closing up (contractility). 
This is illustrated by the action of the contractile vacuole 
of the slime moulds and of many animalcules and by all 
the muscular movements of animals. 
(7) Sensitiveness when touched or otherwise disturbed, 
for instance, by a change of light or of temperature 
(erritability). 
