528 THE THIRD HUXLEY LECTURE 



and again on the same cells with the same results. But if the warmth was 

 allowed to act for a shghtly longer time, or the cautery was made still hotter, 

 recovery never took place, and the bodies of the cells swelled up through endos- 

 motic imbibition of water, having lost all life and obeying the ordinary laws 

 of chemistry. 



This simple experiment was in various ways instructive. It indicated 

 that ciliated epithelium cells, like the pigment-cells, when acted on by a 

 destructive agency to a degree just short of that which is lethal, are thrown 

 into a state in which their vital functions are suspended but not irretrievably 

 lost. It also showed that the cells which compose the animal organism are 

 individually capable of recovering from this state of suspended vital energy, 

 without any aid from the general circulation or the nervous system. 



It further illustrated the important fact that a most injurious agent when 

 operating very mildly may stimulate function without impairing power.^ 



Active congestion, or arterial dilatation with consequent free flow of blood 

 through the capillaries, is an early and prominent symptom of inflammation of 

 a vascular part in man. Unlike the morbid condition which is produced by 

 the application of irritants to the frog's web, it is brought about indirectly 

 through the nervous system. A striking illustration of this was presented 

 in a case which occurred at the period to which I have been referring. A 

 scirrhous mamma had been removed by transverse incisions, together with a 

 considerable amount of integument ; and the cutaneous margins had been 

 brought together, in spite of a good deal of tension, by means of a few stitches. 

 Two days later I found the lips of the wound gaping slightly ; but the sutures, 

 though subjected to much traction, were still holding ; while the skin presented 

 an inflammatory blush extending both upward and downward from the wound, 

 so that it occupied an area of about four inches in breadth. I removed the 

 sutures, and I particularly noticed that no blood escaped from any stitch-track. 

 The procedure occupied about two minutes and (to quote from a note taken 

 at the time) ' no sooner had I done this than I observed that the redness had 

 almost entirely disappeared ; most parts that were before apparently intensely 

 inflamed being now pale '. The irritating agents acted directly on only a minute 

 portion of tissue ; but they induced widespread active congestion, which 

 subsided at once on their removal. Such results could only have been brought 

 about through the agency of the nervous system. 



As I before had occasion to remark, active congestion takes place throughout 



^ It would appear that all agents that act with destructive effect upon the tissues produce suspension 

 of vital energy without loss of life when operating in a minor degree. Whether all such agents are also 

 stimulants of function when in a still milder form is quite another question. 



