CHAPTER VII. 

 PROTOPLASM. 



THE word " protoplasm " was invented in the 

 year 1846, by the eminent German botanist 

 Von Mohl, as a name for one portion of those 

 nitrogenous contents of the cells of living 

 plants, the close chemical resemblance of which 

 to the essential constituents of living animals 

 had been in that same year, emphatically 

 pointed out by the botanist Payen. But if, 

 pushing our investigation beyond the origin of 

 the name, we inquire as to the nature of the 

 thing, and ask What is Protoplasm ? the answer 

 to that question involves a reference to the 

 historical progress of the physiological cell 

 theory. 



That theory may be said to have wholly 

 grown up since Dr. John Hunter wrote his 

 celebrated work " On the Nature of the Blood." 

 According to Dr. Hunter, new growths de- 

 pended on an exudation of the plasma of the 

 blood, in which, by virtue of its own plasticity, 



