PROTOPLASM, THE SEAT OF LIFE. 331 
separated itself from the surrounding cell-substance (proto- 
plasma). As we have already pointed out, the cells, with 
their simple attributes, are so many citizens, who by 
co-operation and differentiation build up the body of even 
the most perfect organism; this being, as it were, a cell 
republic (p. 301). The fully developed form and the vital 
phenomena of such an organism are determined solely by the 
activities of these small albuminous corpuscles. 
It may be considered as one of the greatest triumphs of 
recent biology, especially of the theory of tissues, that we 
are now able to trace the wonder of the phenomena of life 
to these substances, and that we can demonstrate the 
infinitely manifold and complicated physical and chemical 
properties of the albwminous bodies to be the real cause of 
organic or vital phenomena. All the different forms of 
organisms are simply and directly the result of the combi- 
nation of the different forms of cells. The infinitely 
manifold varieties of form, size,and combination of the cells 
have arisen only gradually by the division of labour, and by 
the gradual adaptation of the simple homogeneous lumps of 
plasma, which originally were the only constituents of the 
cell-mass. From this it follows of necessity that the 
fundamental phenomena of life—nutrition and generation— 
in their highest manifestations, as well as in their simplest 
expressions, must also be traced to the material nature of 
that albuminous formative substance. The other vital 
activities are gradually evolved from these two. Thus, 
then, the general explanation of life is now no more 
difficult to us than the explanation of the physical properties 
of inorganic bodies. All vital phenomena and formative 
processes of organisms are as directly dependent upon the 
