CHAPTER III 
THE CELL 
19. Historical. The advancement of our knowledge 
of nature has often depended upon the invention of some 
new instrument that made possible observations that 
could not have been made without its aid. The balance 
did this for chemistry, the telescope for astronomy, the 
thermometer for medicine. The possibilities for under- 
standing plant life were more than doubled by the in- 
vention of the compound microscope. By its aid the 
study of the finer internal structure of plants was made 
possible. 
20. Robert Hooke. One of the earliest to employ the 
microscope in this way was Robert Hooke (1635-1703) 
of England. He was at first interested in demonstrating 
the powers of the microscope on various objects. Among 
them he tried thin sections of cork, and found the cork to 
be composed of little compartments, which he called 
cells, since they roughly resembled the cells of a honey- 
comb. Marcello Malpighi (1674), an Italian, and Nehe- 
miah Grew, an Englishman (1682), greatly extended the 
microscopic study of plants, adding so much to our knowl- 
edge that they are now often referred to as the fathers of 
plant anatomy. 
21. Protoplasm. At first the attention of botanists 
was devoted almost exclusively to the walls of these cell- 
like compartments, and to their shape and arrangement. 
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