ORIGIN OF DISEASE AND THE GERM THEORY. 149 



general occurrence on the right side, just as, similarly, the greater 

 frequency with which embolism manifests itself in the left kidney 

 as compared with the right kidney is attributable to the more 

 direct course of blood to the former. 



In short, numerous connections are to be traced among the 

 phenomena of the diseases and disorders of animals which point 

 unmistakably to a gradual development. How very important 

 it is that such connections should be traced will be readily seen. 



We now come in due course to another division of our subject, 

 namely to that of some '' Abnormal Functional Manifestations of 

 Evolution." 



The functions of an organism, or of the whole aggregate of 

 organisms, no less than the structures of an organism or of the 

 whole aggregate of organisms, are most intimately connected one 

 with another. 



Indeed the mutual interdependence of functions is almost 

 universally admitted. The assertion that the various processes 

 of change going on in a higher animal, that is, its functions have 

 been evolved in association with one another, has been amply 

 supported both inductively and deductively. The phrase 

 " associated functions," like the corresponding idea of " corre- 

 lated structures " expresses a great and undeniable truth. 



A canary, when building in captivity, may be seen to fly about 

 its cage with the straw before placing it in position, that is to 

 say, it unnecessarily attempts to do, under altered circumstances, 

 things which canaries, when making their nests under the 

 ordinary conditions of nature, are actually compelled to do. 

 Though, then, in new circumstances, both animals and man 

 acquire new habits, still, in many cases, relics of the old ones 

 remain. Those functions which will persist for the longest 

 time are those which have, by any means whatsoever, been most 

 strongly impressed upon the organism or upon its progenitors. 



If we examine carefully all the numerous processes undergone 

 by animals, we shall see that they may roughly be divided into, 

 two sets, viz. those of work and those of rest. It is quite true 

 that these two sets are not entirely distinct, but rather they are 

 intimately connected together somewhat in a similar manner to 

 that which links together heat and cold, or light and darkness. 



We shall find it convenient to speak of the one group of 

 functions as the associates of work, and of the other as the 



