2506 ON THE EARLY STAGES OF INFLAMMATION 
stagnant. Yet throughout this space the pigment retained exactly the same 
moderate degree of diffusion as it had at the beginning of the experiment, 
although in the interval complete concentration had taken place elsewhere ; 
and a very striking contrast was presented between the stellate pigment with 
the adhesive though still moving blood-corpuscles, where the web was wet with 
the vinegar, and the dotted pigment and perfectly healthy circulation in the dry 
parts immediately adjacent. 
Seeing, then, that complete suspension of the pigmentary functions may be 
caused by an amount of irritation which induces only a minor degree of congestion, 
and further, that (as we learn from the experiment with chloroform vapour) 
a still milder operation of an irritant renders these functions sluggish though 
not completely arresting them, we seem to have sufficient evidence that impair- 
ment of the functional activity of the chromatophorous cells occurs in the very 
earliest stages of that primary change in the tissues which leads to inflammatory 
derangement of the blood. 
It was seen in the ammonia experiment related above, that resolution 
having taken place in the congested area, the pigment-cells of the part recovered 
the faculty both of diffusion and concentration. This might have been pretty 
confidently predicted; for as congestion is a necessary consequence of the 
disorder produced in the tissues by irritants, we might have been almost sure 
that the return of the vital fluid to that healthy condition in which it 1s fit for 
free transmission through the vessels, must be preceded by a restoration of 
the living solids to their normal state. In the case alluded to, however, no sign 
of recovery of the pigment-cells appeared till after the circulation had become 
re-established ; and even when several hours had elapsed, they still remained 
paralysed in the central part of the area on which the ammonia had acted. 
This is in harmony with the fact lately pointed out, that complete suspension 
of the pigmentary functions may accompany a state of the blood short of actual 
stagnation ; and both appear to depend upon the circumstance that the chro- 
matophorous cells are an extremely delicate form of tissue. 
The rate of recovery of the pigment-cells varies greatly, however, in different 
cases, and in this respect much depends upon the nature of the irritant. An 
example of an agent of this class producing only very transient effects on the 
pigmentary functions is presented by carbonic acid. It has been before men- 
tioned that the immersion of a living frog for about a quarter of an hour in 
water highly charged with that gas, gives rise to complete stagnation of the 
blood in the webs, although the heart still continues beating, but that resolution 
occurs after the animal has been exposed for a while to the atmosphere. With 
a view to ascertaining whether the congestion was due to the direct action of 
