312 Concluding Remarks 



find, and certainly to a revision of the kind of language in which we 

 express our results. I think that if we adopt a more descriptive 

 terminology, and do not imply that one type of organism is inferior 

 to another, the physiologist, at least, can feel a little satisfaction. 



My third point is that we have not done much in this conference 

 with the description of the intake side of metabolism ; we have talked 

 about water and electrolytes almost entirely from the point of view 

 of output. I realize that we all think that we know a little more 

 about output than we do about intake, but perhaps we should have 

 made up our minds before we began the meeting that we knew 

 enough about outputs to feel semi-comfortable and that we knew 

 sufficiently little about intakes to feel distinctly uncomfortable, so 

 we might plan to see what we can find out about them. Lots of 

 people think that a regulation consists in an organism taking in 

 everything in sight and then getting rid of what is excessive. In my 

 experience this is a distinct misconception because where intakes have 

 been studied, we find that they are at least as accurately regulated 

 and controlled as outputs. If you give an animal a water deficit of 

 5 per cent of the body weight and see how much water it takes in the 

 first half-hour of recovery from that deficit, you will find that its 

 accuracy of intake is equal to its accuracy of output when it has an 

 excess of water from the body of 5 per cent. This accuracy, then, is 

 of a kind that must be assessed when we talk about intakes. The 

 intakes are, so far as we know, specific in a number of instances. We 

 have not been able to recognize specific ways in which the organism 

 responds to each of its deficiencies, but we know that there are 

 specific recognitions for sodium, and there may be more specific 

 recognitions for some of the other components. If we can see how 

 the organism relates its intake to its deficits, and how specific those 

 relations are, we shall have made the sort of quantitative progress 

 that we have already been able to recognize with respect to excretion. 



Davson: Prof. Adolph has spoken as a physiologist, and there is 

 very little left for me to do, except to re-emphasize what he has said. 

 The organism is most dependent upon the reactions of certain critical 

 cells which respond to minute changes in their environment, such as 

 changes in magnesium concentration. It seems quite miraculous that 

 the cell could respond in these circumstances; we know that it can 

 respond to a large jump in its external potassium, and we think we 

 know the theory of that, but we are usually concerned with barely 

 measurable changes in the cell's environment. Consider, say, the 

 olfactory organ. There you have a concentration of gas which is quite 

 undetectable by any chemical means and yet one can detect the 

 presence of this gas ; that means that your cell is responding to some 

 infinitely small change in its environment and, as Prof. Adolph has 



