BIOTIC STRUCTURE AND BIOTIC ENERGY 3 



the lungs stopped working so that the blood sent round by the heart 

 contained no oxygen when it arrived at the tissues, then, the 

 necessary oxygen to oxidise the chemical substances and set energy 

 free from them for the work of the cell not being forthcoming, 

 the operations of the cell must abruptly come to a close. 



Such a catastrophe is averted by the minute chemical and 

 colloidal structure of the master cells of cardiac and nervous tissues 

 which regulate these fundamental vital processes. The colloidal 

 matter of these cells is so constituted chemically that they are made 

 oscillating or rhythmic in their discharges, and hence cannot be- 

 come fatigued or overdriven. The two rhythms of respiration and 

 heart- beat bear normally the ratio in their frequency of one to four 

 or one to five that is to say, there are four to five heart-beats to 

 each respiration. And as the two processes possess the combined 

 and complementary function of sending round an adequate supply of 

 sufficiently oxygenated blood to the tissues this ratio is usually well 

 maintained and the two rates go up or down together. It has been 

 shown by Haldane and Priestley that the rate of working of these 

 two fundamental systems is dependent upon a very simple chemical 

 circumstance viz., the amount of the chief gaseous product of com- 

 bustion which is for the moment present in the lung spaces. If the 

 amount of carbon dioxide in the air spaces of the lungs rises then 

 the rates of heart-beat and respiration increase so as to get rid of it, 

 and if the amount falls below normal the heart-beat and breathing 

 become slower and more quiescent. This is the fundamental, prim- 

 ary thing which explains many different secondary causes in the way 

 of varying tissue activity leading invariably through carbon-dioxide 

 variations to varied rates of working of the blood and air pumps. 



When we trace back the chemical bearings of this regulation, we 

 see that variation in amount of carbon dioxide in the air of the lungs 

 means variation in the amount dissolved in the blood, and this again 

 variation in the osmotic pressure of carbon dioxide in the nerve 

 cells and heart cells. But it is now well known, as was first clearly 

 shown by A. D. Waller for nerve and muscle, that the first effect 

 upon all living cells, and hence on both the nerve cell and its pro- 

 cesses and the heart cells, of slight excess of carbon dioxide is to 

 stimulate to increased activity. Later, if the increased amount of 

 carbon dioxide be pushed further the effect is gradually to still all 

 cellular activity. This, for example, is precisely what happens in 

 suffocation : after a period of violent struggling, with exaggerated 



