22 BIOLOGICAL PHYSICS 



the central stage, or acme, of the metabolism of nutrition, 

 where the currency of new pabulum is given in exchange 

 for the currency of effete, effaced, or damaged tissue 

 elements, in the proportion of atom for atom, and mole- 

 cule for molecule, with rigorous exactitude, and to the 

 entire satisfaction of mutual needs. All the fluids met 

 with in the body are consequently but derivatives from 

 this fluid, serving some special purpose, and returning 

 to the parent source, or being excreted as no longer neces- 

 sary, or, it may be, hurtful to the economy of circulation 

 and nutrition ; thus, serum in all its varieties, synovia, 

 sweat, sensible and insensible, glandular excretions, and 

 the great systemic evacuations, represent the purposive 

 utilisation and disposal of this universally disposed fluid 

 for systemic necessities, local and general, and for the 

 accomplishment of the "thousand and one" vital pro- 

 cesses occurring and recurring within the vital areas. The 

 circulation of this fluid is effected on lines beginning 

 with, and flowing from, ingestion, and terminating with 

 egestion, or shedding through vascular systems proper, or 

 by quasi-solid fibres composed of fibrils, with connecting 

 spaces and inter-spaces, from the considerable to the 

 atomic, where the passage of the mass and the molecule are 

 alike provided for, the whole constituting a system of 

 graduated and onwardly progressive circulation through 

 inter-material, sponge-like space and inter-space areas, from 

 the interior of which the tissues proper extract or receive 

 their needed pabulum, and convert it into their proper 

 substance by their inherent vital powers, returning it by 

 an inverse order of procedure. 



This universal system of circulation requires for its per- 

 formance an uninterrupted succession of circulatory ways, 

 from its inception to its close, hence solidarity, as it is 

 to be met with in the matrix of organic substances, can 

 only be relative, and we must be prepared to find that 

 nutrition is only possible so long as these circulatory ways 

 remain patent and pervious, to the ever onward passage of 

 the lymph streams, in which are held in solution, or sus- 

 pension, the prospective tissue elements in the cis-nutritive 

 lymph, and the retrospective tissue elements in the trans- 

 nutritive lymph. The existence, therefore, of impervious 



