CHAP, vi.] OF LIVING LIQUIDS. 59 



posed monocellular organisms. However there is usually a gene- 

 ral enveloping membrane and afterwards an interstitial liquid, 

 a sort of blastema, playing, in respect to the anatomical elements 

 of the polycellular organism, the part of an artificial medium. 

 The cells now no longer plunge direct into the cosmic medium ; 

 they are protected and isolated by an organic, an elaborated 

 liquid. In the extremely complex organisms, for instance, in the 

 superior animals, the intrication of the texture is much greater. 

 Here the anatomical elements are not formed in one mould only ; 

 they are differentiated according to multiple types, and each type 

 assumes a diverse function. One, for instance the epithelial type, 

 supplies to the living membranes a protecting varnish ; to the 

 glands a special agent of secretion; another, for example, the 

 tissue called cellular, serves as gangue, as bond, as support to all 

 the tissues, apparatus and organs, while opening besides a passage 

 to blastematic liquids. A third, exemplified in the osseous 

 element, furnishes to the organism a solid framework. Lastly, 

 the muscular fibre and cell impress on the pieces of the living 

 apparatus the necessary movements, while the nervose fibre and 

 cell endow the organism with sensibility, with will, with thought, 

 and are the sentient soul of the entire being, of which they 

 assume the conscious direction, and so on. But in order that 

 these anatomical elements so diverse, so numerous, grouped into 

 tissues, into organs, into apparatus, into special systems, may 

 live, may perform their functions, may co-operate, it is needful for 

 them to be almost completely withdrawn from the rough and 

 capricious influences of the exterior world ; they must perform 

 their functions in an artificial medium, alive like themselves, in 

 which they find a temperature little variable, a magazine always 

 well provisioned with substances elaborated and assimilable, suited 

 to repair their losses ; Lastly, a place of discharge, into which they 

 throw their used materials, that have become unfit to figure 

 in the vital movement. These nutritive media, artificial, liquid, 

 consequently appropriate for the aquatic life of the anatomical 

 elements, are the plasmas, always in movement, always renewed, 



