ON RESPIRATION 513 



to a greater degree than the latter does, even with the 

 assistance of " printed rules." 



Referring further to the two great blood constituents 

 the corpuscular and the liquor sanguinis it may be 

 remarked that the former, at least the red corpuscles, 

 acts from within the blood-stream, in effecting those 

 metabolic processes in the economy of nutrition for which 

 it is responsible, with the exception of what is effected by 

 the " wandering cells " which escape through the inter- 

 stices of the lining vascular endothelium to perform most 

 important hygienic, and other more or less known physio- 

 logical work in extra-vascular regions this, of course, 

 refers to the non-red corpuscles only the latter, the 

 liquor sanguinis, escapes through the vascular endothelium 

 by, we would suppose, cell agency, into the cells and 

 fibres, or cell processes, of the whole so-called extra- 

 vascular structures of the body, and into the stroma of 

 the systemic nervine basis, the neuroglia, when it is 

 utilised by the extra-vascular, or sympathetically in- 

 nervated structures, and the systemic nerve structures, 

 with their muscular and other continuations respectively. 



The red corpuscles thus never leave the blood-stream, 

 continuing to circulate therein while its vasculature re- 

 mains intact, but disseminate their nutritive materials and 

 chemico-physical energy by cell and fibre continuity to 

 the most distant parts and structural elements of the 

 body ; the white corpuscles, however, are allowed a 

 greater latitude of movement, in that they are permitted 

 to penetrate to the regions lying outside the blood vascu- 

 lature, where their phagocytic and anti-pathogenic powers 

 are utilised in maintaining tissue hygiene, and promoting 

 extra-vascular physiological change and circulation within 

 the compass and reach of their somewhat extended oppor- 

 tunities and vital powers. The liquor sanguinis, from 

 its lymphoid character, necessarily may penetrate the walls 

 of the entire blood vasculature, by osmosis, and pass 

 directly through those apertures in it permeable by the 

 white corpuscles, but we must be prepared to find that its 

 nutrient circulatory distribution is confined within such 

 limits as secure its reaching, in its physiologically pure 

 state, the tissues whose wants it is destined to supply in 



2 K 



