4: MANUAL OF BOTANY. 



molluscous and other animals. The presence of starch was also 

 formerly considered as a certain characteristic of a plant, but 

 recent investigations have also shown that this substance, or at 

 least one isomeric with it, is also to be found in the tissues of 

 animals. Neither the presence of cellulose or starch can be now 

 considered, therefore, as presenting any absolute marks of dis- 

 tinction between plants and animals. We arrive accordingly 

 at the conclusion that it is impossible to give a complete and 

 perfect definition of a plant, in contradistinction to what is to 

 be regarded as an animal. 



