132 THE DISEASES AND DISORDERS OF THE OX. 



pathology is in reality not only to be accepted in itself as un- 

 questionably true, but is rather, as we hope to show, to be 

 accounted as one of the supports of evolution at large. If it 

 is true that the numerous and involved processes which 

 make up healthy life in all its many varied forms and phases 

 are to be considered in connection not only with one another, 

 but also with the phenomema from time to time occurring 

 in the outside world, it is also no less true that the general 

 statement applies with just the same force to the facts of crea- 

 tures suffering from disease, as it does to the normal functions 

 of healthy living beings. 



We hope that we may, in some degree at least, succeed in 

 pointing out some few facts of disease which will bear out this 

 statement, and also in attempting to indicate causation in some 

 instances where at first sight even connection may not be easily 

 traced. It is, however, sufficiently manifest that, though we can 

 to a large extent say definitely of many given structures and 

 functions that they are either normal or abnormal, as the case 

 may be, there are instances in which it is extremely difficult to 

 draw the line of demarcation, and it is quite evident that 

 the same law of causation which we suppose to be applicable 

 to the one group applies with equal force to the other. If 

 a structure is disorganised, or a function vitiated or altered, 

 there must always be a cause, could we but trace it, for the 

 change which has resulted. The origin of the alteration may be 

 ever so remote. We may possibly have to look back to a far 

 distant point of time, to progenitors of a bygone age. Still the 

 cause has existed in some form at some time. 



Perhaps one of the most important of all the possible indica- 

 tions concerning pathology is that the various diseases and 

 disorders which are liable to afflict human beings present relation- 

 ships with those of lower animals, just as, indeed, other human 

 characteristics, whether structural in nature or functional, are 

 likewise related in certain ways to those of organisms lower in 

 the scale of vitality. Even now the evidence which supports 

 this generalisation is very strong indeed, although the science 

 of pathology has as yet been only cursorily studied from the 

 comparative point of view. As yet men have scarcely learned 

 to fully realise the incalculable advantages capable of being 

 derived from investigating the diseases of human beings by the 



