PHYSIOLOGY AND MORPHOLOGY OF ANIMALS. 



Protista 



Animals vs. Plants.— The distinctions between ani- 

 mals and plants are apparently so obvious that it may 

 seem useless to draw attention to them, but it is so only 

 to careless view and in compar- 

 ing the higher members of the 

 two kingdoms. As we descend 

 in the scale the two kingdoms 

 approach more and more, until 

 they absolutely come together — 

 in other words, the living king- 

 dom in its lowest members 

 consists of beings which are 

 both animals and plants, or else 

 Fl V^Sn^LTof neither. They are living things 

 animals and plants from without further qualification. In 

 Protista. J / , , 



the present state of our knowl- 

 edge they may be claimed by either botany or zoology, 

 and it is proposed to call them Protista, or lowest living 

 beings. From these lowest beginnings the two kingdoms 

 separate more and more as we rise. Where they first 

 separate we call them Protozoa (first or lowest animals) 

 and Protophyta (first or lowest plants). Then follow the 

 more distinctive animals and plants, but the animals rise 

 the higher, as in Fig. i. 



It is not so easy, then, to define the limits of the 

 animal kingdom. Popularly, perhaps, animals would be 

 defined as beings capable of motion ; but this will not do, 

 for many plants also move under stimulus, as, for exam- 

 ple, the sensitive plant. Or perhaps locomotion is sup- 

 posed to be characteristic of animals; but this also 

 fails, because many of the lower plants and the embryos 

 of some higher ones move about with such rapidity 

 that they can hardly be observed carefully under the 

 microscope. On the other hand, many animals some- 

 what high in the scale, such as oysters, corals, etc. 



