CHAPTER III. 



To what extent Structural Abnormality occurs during the Actual 

 Time of Disease. 



We have seen that it is by no means easy to say offhand what 

 constitutes normality of structure. Although it is impossible 

 to fix any criterion of abnormality available for all, it is 

 nevertheless convenient to have some sort of criterion, other- 

 wise it would often be impossible to say of any given structure 

 that it was abnormal, for we could never be certain that there 

 might not be an E somewhere in which that S could carry 

 on its functions normally. 



There are two tests whereby to judge of the abnormality. 

 The first is examination of the structure either with the naked 

 eye or by the aid of the microscope. We are in this way able 

 to discover certain structural states which our knowledge of 

 normal anatomy, macroscopic and microscopic, tells us are 

 abnormal beyond any doubt. The criterion here is experience. 

 We should not be justified in regarding any structural appear- 

 ance as abnormal unless it differed beyond all manner of doubt 

 from the condition obtaining in the vast majority of ordinary 

 healthy human beings. 



But although by the examination of a tissue we can, in many 

 instances, pronounce it to be abnormal beyond all question, we 

 cannot, conversely, be certain that it is normal if we fail to 

 detect structural alterations, for the tissue may be the seat of 

 some subtle structural change altogether beyond the reach of 

 discovery. These remarks apply more particularly to nerve 

 centres, in which the finest shades of structural change may 

 mean all the difference between perfect health and serious 

 disease. They do not apply with equal force to the cruder 

 tissues — such, for instance, as the connective tissues. If a 

 practised observer fails to detect altered structure in these, we 



