430 LECTURE XVII. 



first question is, what conception we are to form of such 

 a stimulus. 



We have already seen that the irritation may in gene- 

 ral be traced to one of three different sources, accord- 

 ing as it is a functional, nutritive or formative irritation 

 which has taken place. Now there can be no doubt, 

 but that functional stimuli (irritaments) do not play an 

 essential part in inflammation, and for the simple reason, 

 that a point upon which all the more recent schools at 

 least are agreed to the four characteristic symptoms 

 lexion of function (functio laesa) must be added. 



If there be a disturbance of function in inflammation, 

 this presupposes that the inflammatory stimulus (irrita- 

 ment) must be of such a nature as to cause changes in 

 the composition of the part which render it less capable 

 of performing its functions. Nobody would expect a 

 muscle which is inflamed, to perform its functions nor- 

 mally ; every one supposes that the contractile sub- 

 stance of the muscle has thereby experienced certain 

 changes. Nobody would expect an inflamed gland-cell 

 could secrete normally, but we should look upon the 

 disturbance of secretion as a necessary consequence of 

 the inflammation. Nobody could expect an inflamed 

 ganglion-cell or nerve to discharge its functions, or nor- 

 mally to respond to stimuli. The conclusion, therefore, 



(subsequently) provokes changes in the neighbouring parts not directly altered by 

 the irritant the consequence of which is their action or reaction. This condition, 

 which is an active one, based upon the physiological powers of the parts, represents 

 irritation in the proper sense of the word, and as the starting-point in every form 

 of inflammation. See Archiv f. path. Anat. uud Phys. vol. xiv., p. i. (Reizung und 

 Beizbarkeit). 



The matter will perhaps be rendered clearer by the following familiar illustration : 

 Suppose three people were sitting quietly on a bench, and suddenly a stone came 

 and injured one of them, the others would be excited, not only by the sudden 

 appearance of the stone, but also by the injury done to their companion, to whose 

 help they would feel bound to hasten. Here the stone would be the irritant, the 

 injury the irritament, the help an expression of the irritation called forth in the 

 bystanders. From a MS. Note by the Author. 



