118 W. A. Osborne: Oscillatory Adjustments. 



one nerve cell discharging after the other. This is the causative 

 factor usually assumed. But the rhythm due to absence of mechani- 

 cal fixation and absolutely necessitated by the adjustments based 

 on sensory impressions is left out of count. 



IV. The Blood Constants. — The blood of the higher animals dis- 

 plays remarkable constancy in a number of its characters. Deter- 

 minations of hydrogen ion concentration have shown that the range 

 of reaction, despite almost gross variations in the reaction of food 

 and of metabolites, is exceedingly small. Here the kidney and lungs 

 are the organs entrusted with the standardisation, or, at least, with 

 tlie fine adjustment of the standardisation. There is similarly a 

 constancy with respect to osmotic pressure, metallic balance and 

 water content, and again the kidney is the regulating organ. If 

 an oscillation in any of these properties were sought for it v.-ould 

 be in the blood from the renal vein, but one might well expect the 

 oscillations to be so small and so damped that they would escape 

 detection. Yet it is surely possible that pathological conditions 

 might exist which would magnify such oscillations and make them 

 detectable and of import to the functioning of the tissues of the 

 body generally. 



Arteriolar vaso-constriction is a local variable adjusted to the 

 varying action of gravity on each part of the body and to the 

 varying call for blood from the organs as they are severally excited. 

 Yet there is a mean blood pressure and self-regulating devices, such 

 as the depressor nerve or the direct action of high pressure on the 

 medulla, have been proved to exist. Though once more the oscilla- 

 tions produced may be too small and too damped to be made mani- 

 fest, it is again possible to assume that they may be greatly exag- 

 gerated in pathological states. 



What determines the total quantity of blood in the body, the con- 

 centration of plasma proteins, and the number of formed elements, 

 physiology as yet has not determined, but if self-regulating 

 mechanisms are at work, the same argument applies. 



The above are a few only of the self-adjusting processes in the 

 body. There are many others not touched upon. One has only to 

 think of the reflex excitation of the lachrymal gland, which is so 

 finely adjusted that lx)th dryness and excessive moisture of the 

 cornea are avoided, of the secretion of mucous surfaces, of the 

 growth of the skin pari-passu with frictional loss and such like, to 

 lealise that self-adjustment is the rule and not the exception. And 

 in all self-adjusting systems, we may venture to state, rhythm, if 

 not apparent, is latent, and can be brought into prominence by 

 pathological changes. 



