164 ON VAEIABILITY AND ADAPTATION 



manifest this reaction on the part of their vessels in response 

 to stimuli of a certain order, whereas those who did not were 

 more unfavourably placed and so succumbed ; that they con- 

 veyed the same power to their descendants who also possessed 

 this advantage over individuals incapable of affording the 

 reaction ; then we can conceive the development of a race 

 possessing a mechanism for countering a given stimulus by a 

 given reaction, a race in which provision is made, or gained, for 

 dealing with a given order of events ; then it will be seen that 

 what primarily is accidental becomes secondarily purposeful 

 through the survival of the fittest and the inheritance of defensive 

 acquirements. The tissues thus become prepared to respond 

 to certain alterations in their environment. In other words, 

 " natural selection " renders what was primarily accidental, 

 secondarily purposeful. 



The whole process of inflammation is an exemplification of 

 " adaptation," and we would strongly commend the address by 

 Professor Welch x upon this subject to those desirous of gaining 

 a right point of view regarding pathological processes in general. 

 For living matter to survive, it must be adapted to its environ- 

 ment, and this in the first place happens through inheritance, 

 through the survival of the fittest, along the lines laid down 

 above. 



Yet in the study of inflammation we are compelled to re- 

 cognize, not merely inherited, but also individual adaptation. 

 We cannot otherwise explain why it is that bacteria, which at 

 first exhibit active local growth within the tissues, become 

 eventually destroyed on the resolution of the inflammatory 

 state, unless we acknowledge that the cells, or certain of them, 

 acquire and, it must be, transmit, increased bacteriolytic and 

 antitoxic properties. The facts gained regarding the develop- 

 ment of immunity — the presence in the body-fluids of the 

 immunized animal of substances inimical to the infective agents, 

 which are absent, or present in but minimal amounts, in the 

 fluids of the untreated animal — all demonstrate this individual 

 adaptation. At the present time, indeed, workers all over 

 the civilized world are busy in researches bearing upon this very 

 subject, the production and mode of action of what may be 

 termed, generically, antibodies. 



* Welch, Amer. Jonrn. of ike Med. Sciences, 1897, oxiii 631. 



