BOTANY. 



PART I. 

 GENERAL MATOMY AND PHYSIOLOGY. 



CHAPTER I. 



PEOTOPLASM. 



1. — If we examine a thin slice of any growing part of a 

 plant (Pig. 1) under a microscope of a moderately high 

 power (400 to 500 diameters), there may be seen large num- 

 bers of cavities which are more or less filled with an almost 

 transparent semi-fluid substance. In very young parts, as 

 in buds and the tips of roots, this substance entirely fills the 

 cavities, and makes up almost the whole mass, while in older 

 parts it occurs in less quantity, and usually disappears in 

 quite old tissues. This substance is the living portion of 

 the plant, the active, vital thing which gives to it its sensi- 

 bility to heat, cold, and other agents, and the power of mov- 

 ing, of appropriating food, and of increasing its size ; it is, in 

 fact, tJiat which is sensitive, which moves, appropriates food, 

 and increases in size. This sensitive, moving, assimilating, 

 and growing substance is named Protoplasm.* 



It is a fact of great biological interest that in animals the essential 

 constituent of all living parts is a substance similar to the protoplasm 

 of plants. We cannot distinguish the two by any chemical or physical 

 tests, and can only say that, taken as a whole, the protoplasm of plants 



* So named by its discoverer. Dr. Hugo Von Mohl, in 1846. It is the 

 Bioplasm of Dr. Lionel Beale and his followers. 



