LIVING MATTER. 35 



called the lower orders. It is difficult to distinguish in 

 all cases between animals and plants. In the simpler 

 kinds the characters touch and dissolve into each other, 

 so that no exclusive definition is possible. Some natur- 

 alists think that there are organisms which at one period 

 of life are vegetable, and at another animal. 



10. If we consider their origin, both animals and 

 plants begin life as a small particle of bioplasm. In 

 plants this forms an ovule, with wall of cellulose, and 

 in animals it becomes an ovum, or egg, with wall of al- 

 buminous matter. 



11. As to form, we have no means of separating 

 animals and plants. The zoospores of Algae are like 

 Infusoria. Sea-mat 



(Flustra) and Sea- 

 moss (Fig. 4) (Poly- 

 zoa) are like Sea- 

 weeds, (Algae,) Cor- 

 als and Actiniae are 

 like flowers. 



12. In chemical 

 composition, as a 

 rule, plants are des- 

 titute of, and ani- 

 mals are largely 



Supplied With ni- F,G. 4 .-SertulariaO P erculata. 



trogen. Yet there are some animal structures without 

 nitrogen, and some vegetable structures with it. Cellu- 

 lose, (woody fiber,) generally found in vegetables, is 

 wanting in the Fungi, and is found in the covering of 

 Ascidians, (Sea-squirts.) Starch, under the name of 



