MORPHOLOGICAL ELEMENTS OF THE LINING BEING 5 



2 THE PHYSIOLOGICAL SIGNIFICANCE OF THE 

 MORPHOLOGICAL ELEMENTS OF THE LIVING 

 BEING 



The characteristic chemical configuration of the living 

 substance is connected with the structure or organization of 

 the living being. 



The structural elements, from which all living beings are 

 built up, are called cells. The characteristic constituents 

 of each cell are: 



1. The protoplasm, a jelly-like mass, composed of a 

 liquid ground-substance and solid constituents (protoplasmic 

 framework, granules, chromatophores, and other inclosed 

 objects) ; 



2. One or more nuclei found in the protoplasm, generally 

 spherical bodies composed of nuclear framework, nuclear 

 sap, nuclear membrane, and nuclear corpuscles. 



Protoplasm and nucleus are the bearers of life. 



The cells which compose the living being are physiologi- 

 cally of very different value. From a physiological stand- 

 point we can divide them into two groups : 



1. Cells, each of which is an independent living being 

 (physiological individuals), e.g. all unicellular organisms 

 (protists) ; these are cells which possess all physiological 

 activities necessary for the maintenance of life. 



Simpler physiological individuals than cells are not known. 

 Parts of cells (separate protoplasmic masses, single nuclei) are not 

 capable of independent existence. 



2. Cells not capable of existence by themselves, but only 

 in physiological connection with other cells, for in them, as 

 in the members of an organism, some physiological processes 

 are strongly developed, while others are more or less 

 undeveloped and taken up by cells of another kind. In this 

 case many cells together build the physiological individual, 

 and the processes necessary for the maintenance of life are 

 distributed among the different cells of the individual. As 

 in such cells the specially developed physiological processes 



