THE PHYSICAL BASIS OF LIFE 269 
the botanist Nageli had studied this living substance, and 
perceived that it was nitrogenous matter. This was a dis- 
tinct step in advance of the vague and indefinite idea of 
Schleiden, who had in reality noticed protoplasm in 1838, 
but thought of it merely as gum. The highly accomplished 
investigator Nageli (Fig. 84) made a great place for himself 
Fic. 85.—Huco von Mout, 1805-1872. 
in botanical investigation, and his name is connected with 
several fundamental ideas of biology. To Von Mohl, how- 
ever, belongs the credit of having brought the word proto- 
plasm into general use. He stands in the direct line of 
development, while Purkinje, who first employed the word 
