CONCLUDING REMARKS 



Adolph: It is easier, I find, to mention some of the things we have 

 omitted in this colloquium than to dwell on some of the things that 

 we have gone into. We are all concerned with studies of regulation, 

 some of us as observers of normal individuals and some of us by 

 trying to cut in on the mediators by administering hormones. Per- 

 haps the most important element in metabolic events, particularly in 

 respect to water and electrolytes, may be the detection by the body 

 and the cells themselves of departures from the normal. In other 

 words, we must recognize that for each one of the constituents which 

 we have been talking about as having a constancy, there is some sort 

 of a detection machine. The fact that there are so many machines 

 all in one small body or cell is something to bear in mind. Since 

 regulation involves intrinsic detections both for the body as a whole 

 and for each constituent compartment, how is it that we had nothing 

 to say about the cell's own assessment of its state? I suppose it is 

 entirely because nobody so far has found a method of cutting in on 

 messages which are being transmitted from the surface of a cell to 

 the interior of a cell, or the kinds of excitation which occur to produce 

 the response within a cell. If we could find out whether these detec- 

 tors and transmitters, if there be such, differ at differing ages, then 

 we would have a more intimate picture of physiological changes with 

 age. So far we have mainly had to content ourselves with seeing 

 whether we could show some morphological or biochemical change 

 with age. As I see it we have not yet got down to what a physiologist 

 could be really proud of in the measurement of age changes. In my 

 estimation we do not need to wait until we know what the nature of 

 these detectors and transmitters may be before we can tackle these 

 problems of assessment of the state of the responding system. We 

 can study many a responding system without having any knowledge 

 of the kinds of gadgets which are in it. Our ignorance of cell excita- 

 tions is well founded, I suppose, and yet it is disappointing. I hope 

 the future physiology of cells will, develop a knowledge of these 

 detectors, and of the way they change with age. 



Next I want to try and needle you into thinking of age changes not 

 as changes of immaturity and senescence but as states in the organism 

 which are perhaps optimal for each of the age groups. A man of 80 

 years of age need not necessarily be considered inadequate in any 

 particular respect. If he has not got as high a clearance at 80 as he 

 had at 30, can that mean that he has no use for it? This point of 

 view may lead to a slightly different kind of evaluation of what we 



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