1894] Chemico-Physiological Discoveries: The Cell. 101 
other forms of organic matter, but its energy cannot be made 
available in the manner required by the living animal organ- 
ism. It must first be fitted for assimilation through digestion 
or otherwise; after which, having passed into the circulating 
fluids, it finally reaches the cell under whose influence it un- 
dergoes a final change by which it is raised to a higher plane. 
That which was dead has become alive, a chemical transfor- 
mation has occurred, the atoms in the molecule have been 
rearranged and we have to deal with living matter; a change 
accomplished through the anabolic power of the living cell, or 
better of the cell protoplasm. Anabolism and katabolism, 
construction and destruction, are thus going on continually in 
the living animal cell side by side as a necessary concomitant 
of life, but the processes are not everywhere of the same order. 
They are qualitatively and quantitatively unlike, especially 
the katabolic, the latter showing some peculiarities character- 
istic of almost every individual group of cells as comprised in 
individual organs or tissues. Each individual cell as a com- 
ponent of the many and varied tissues of the organism is to 
be compared to a well equipped chemical laboratory, the 
character and amount of the work produced being dependent 
in part upon the intrinsic qualities of the cell, i. e. of the cell 
protoplasm, and in part upon the nature of its surroundings 
or environment. While these statements apply more particu- 
larly to the animal cell, they are likewise true of the vegetable 
cell, the only difference being that in the latter we find a pre- 
dominance of synthetical processes, a remarkable power of 
building up complex substances such as starch and proteid out 
of the simple food material obtained from the air and the soil, 
while the animal cell is especially characterized by the extent 
of its katabolic processes. 
It is thus very evident that while in the early stages of 
growth and development, all animal cells, for example, may 
show a striking similarity in composition, as soon as differen- 
tiation in form begins to manifest itself with an accompani- 
ment of functional activity, chemical composition is gradually 
altered until at last each group of cells characteristic of the 
individual organs and tissues acquires a composition peculiar 
