66 



the above materials, is accomplished in the circulation, and not in the 

 tissues ; that it is chiefly produced in the arterial system, and com- 

 mences from the moment oxygen is received in the lungs, such action 

 continuing throughout its whole extent ; that such action takes place 

 also in the veins, but to a much less degree ; that the heat necessary to 

 maintain muscular and other tissues at the normal temperature is de- 

 rived from the arterial blood passing through them, and not from any 

 oxidation taking place in their proper tissues ; and that such tempera- 

 ture of individual parts bears a direct ratio to the diameter, or sum of 

 the diameters, of such arteries. 



The means by which the materials, derived from the three separate 

 sources alluded to above gain access to the circulation, I shall consider 

 under three separate heads : — 



First. Ingested fatty foods are delivered into the circulation through 

 the thoracic duct, before reaching the termination of which they have 

 much diminished, the white nucleated cells having absorbed them to a 

 corresponding extent, carrying them into the circulation in an altered 

 condition. 



Second. For the removal of the debris of the tissues — such as active 

 muscular tissue, &c, into the circulation — I attribute to the white cells 

 in the capillaries (whose office has been a rather fertile source of specu- 

 lation), the fulfilment of that important function. 



Third. Such calorifacient materials as exist free in the circulation, 

 whether derived from the ingested food, or stored up adipose tissue — 

 as when the system is labouring under a deficiency of food — the white 

 nucleated cells absorb them into their interior for calorifying pur- 

 poses. 



In fulfilling this secretive function they are converted into the fully 

 formed red cells of the blood, which thereby become the active calori- 

 fying agents of the system — the laboratories, in fact, within which 

 oxidation is rapidly effected, producing as a result carbonic acid, water, 

 and various eliminative compounds, and the evolution of Animal Heat. 



A portion of the oxygen of the red cell substitutes the iron of the 

 hematine ; the iron thus set free acts as the exciting or catalytic cause 

 of union between the remaining free oxygen and such elements of the 

 blood cell as, by oxidation, produce Animal Heat. 



XV. — On the Origin of the South European Plants found grow- 

 ing in the West and South of Ireland. Ey Professor Hen- 

 nessy, F.P. S. [Abstract.] 



[Read May 27, 1867.] 



The author accounted for the circumstance that he brought this subject 

 under the notice of the Academy by the fact, that although he had no 

 pretensions as a botanist, his inquiries regarding the climatology of the 



