SECTION 1C] MOVEMENTS. 149 



they restore an equal hulk of life-sustaining oxygen needful for the respiration 

 of annuals, — needful, also, in a Certain measure, for plants in any work t hey 

 do. For in plants, as well as in animals, work is done at a certain cost. 



§ 6. PLANT WORK AND MOVEMENT. 



453. As the organic basis and truly Living material of plants is identical 



with that of animals, so is the life at botl essentially the same; but In 



animals something is added at every rise from the lowest to highest organ- 

 isms. Action and work in living beings require movement. 



459. Living things move; those not living are only moved. Plants 

 move as truly as do animals. The latter, nourished as they are upon or- 

 ganised food, which has been prepared for them by plants, and is found 

 only here and there, must needs have the power of going after it, of collect- 

 ing it, or at least of taking it in ; which requires them to make spontaneous 

 movements. But ordinary plants, with their wide-spread surface, always 

 in contact with the earth and air on which they feed, — the latter every- 

 where the same, and the former very much so, — might be thought to have 

 no need of movement. Ordinary plants, indeed, have no locomotion ; some 

 float, but most are rooted to the spot where they grew. Yet probably all 

 of them execute various movements which must be as truly self-caused as 

 are those of the lower grades of animals, — movements which are over- 

 looked only because too slow to be directly observed. Nevertheless, the 

 motion of the hour-hand and of the minute-hand of a watch is not less real 

 than that of the second-hand. 



460. Locomotion. Moreover, many microscopic plants living in water 

 are seen to move freely, if not briskly, under the microscope ; and so like- 

 wise do more conspicuous 

 aquatic plants in their embryo- 

 like or seedling state. Even at 

 maturity, species of Oscillaria 

 (such as in Fig. 4S8, minute 

 worm-shaped plants of fresh 

 waters, taking this name from 

 their oscillating motions) freely 

 execute three different kinds 



of movement, the very delicate investing coat of cellulose not impeding the 

 action of the living protoplasm within. Even when this coat is firmer and 

 hardened with a siliceous deposit, such crescent-shaped or boat-shaped 

 one-celled plants as Cfoiteriun OT Naviemia are able in some way to mOVC 

 along from place to place in the water. 



461. Movements in Cells, or Cell-circulation, sometimes called (]i/- 

 closis, has been detected iu so many plants, especially in comparatively 



Fiu. 4fi8. Two individuals ut au Oscillaria, magnified. 



