10 BIOLOGICAL ASPECTS OF HUMAN PROBLEMS 



diaphragm of a telephone receiver. The auditory 

 records or memories in the nervous system bring to 

 mind the continuous records made on the tinfoil of 

 a phonograph. But the revival of the tracings of 

 the phonograph, implicating as it does a process 

 purely physical in its nature, must be very different 

 from the reawakening of memory through the 

 chemical processes which we must assume to under- 

 lie nervous activities. Yet there attaches a deep 

 interest to the idea that the brain may contain 

 materials which fixate in some definite though subtle 

 material way the impressions which act on them; 

 and moreover in such a way that the materials con- 

 cerned in this fixation may on occasion be rearranged 

 so as to revive the original impressions. The rela- 

 tively crude physical analogy of the phonographic 

 tracing is welcome, for it is now the only one we have 

 and may prove the forerunner of knowledge of 

 chemical parallels. 



II 



Enough examples have now been cited to show 

 some notable similarities between animal organisms 

 and artificial machines. These similarities are suffi- 

 ciently profound to create a strong presumption 

 that there are many other resemblances, perhaps 

 less obvious but equally instructive as bearing on 

 the mechanistic hypothesis. Research has, indeed, 

 brought to light an immense body of additional facts 



