chap, i.] ANIMALS AND PLANTS. 17 



Cilio-flagellata have cellulose in their cell-walls, and 

 the so-called matrix of cartilage cells does not appear 

 to be directly formed from the cells themselves. 



This enumeration of differences or resemblances is, 

 after all, unsatisfactory, and will, with the progress of 

 knowledge, come, no doubt, to be regarded as mis- 

 leading ; for the present, it will not fail in its object 

 of impressing on the student the broad and general 

 characteristics of animals and plants as we now know 

 them ; but there must be added to it a reminder that 

 among the higher members of the Droseracese we find 

 plants (a) whose leaves have in some forms the power 

 of movement when excited ; (#) the glands of their 

 leaves are able both to digest and to absorb animal 

 matters ; and (7) the normal electrical current is, 

 when these leaves are irritated, disturbed in the same 

 manner as is that of a contracting animal muscle. 



The general relation of animals to plants is well 

 shown in the following table (Brass) : 



^Plants- 



use up form 



carbonic acid, water, nitrates, oxygen, carbohydrates, fat, albumen, 



form use up 



The fact that, in sunlight, green plants (that is, 

 plants containing chlorophyll) give off oxygen has led 

 some to think that plants take in carbonic acid and 

 exhale oxygen ; but plants as much as animals give off 

 carbonic acid as a waste product. If or when an ani- 

 mal contains chlorophyll grains, it as much as a plant 

 will give off oxvgen under the influence of sunlight. 

 c 16 ' 



