232 ON THE EARLY STAGES OF INFLAMMATION 
puscles, on the other hand, implied an alteration in the properties of the blood, 
viz. an abnormal adhesiveness in the red discs. Determination of blood is thus 
a purely functional phenomenon, and, like a blush upon the cheek, becomes 
obliterated after death by the post mortem contractions of the vessels: inflam- 
matory congestion, on the contrary, is the first evidence of organic lesion, and 
declares itself as distinctly in the dead as in the living, being the most important 
if not the only sign of the early stages of inflammation discoverable on dissection," 
as for instance in the case of incipient meningitis mentioned in the Introduction 
to this paper. 
Although determination of blood, as met with in the frog, is thus entirely 
independent of inflammatory congestion, yet it is of great interest with refer- 
ence to human inflammation. Dilatation of the arteries is now generally 
admitted to be the result of the relaxation of their muscular fibres ; and that 
it is a purely passive phenomenon, seems to be absolutely demonstrated by 
the fact which I have pointed out elsewhere,? that after the vessels have been 
liberated from the control of the nervous system by removal of the spinal cord, 
they dilate fully if the heart continues to act sufficiently powerfully to distend 
them with blood, but not otherwise. Recent physiological discovery has shown 
that the arteries are not singular in being thrown into a state of muscular relaxa- 
tion through irritation of the parts of the nervous system connected with them, 
the same being the case with the heart, the intestines, and apparently also with 
other hollow viscera. In a ‘Preliminary Account of an Inquiry into the Func- 
tions of the Visceral Nerves’, published in the Proceedings of this Society,’ I have 
given some notice of experiments which seem to show that in the case of the 
viscera alluded to, the state of relaxation under such circumstances is the result 
of the more energetic operation of nerves, which, when working more mildly, 
increase the muscular action of the same organs; the functions of the ganglia 
specially concerned in regulating the movements of the viscera being exalted 
by gentle stimulation on the part of the afferent nerves connected with them, 
but depressed by stronger excitation. In that paper the opinion was expressed, 
that the same explanation probably applies to the relaxation of the arteries, 
* Since the reading of the paper, I have pointed out that, in consequence of the persistent fluidity 
of the blood which continues in the smaller vessels for days after death, the red corpuscles have time 
to gravitate into dependent parts, and thus give rise to that appearance of post mortem congestion 
which more or less closely simulates to the naked eye what would have resulted from inflammation during 
life. See a paper by the author ‘On Spontaneous Gangrene from Arteritis and the Causes of Coagulation 
ot the Blood in Diseases of the Blood-vessels’, Edinb. Med. Journal, April 1858 (page 69 of this volume). 
* See pp. 27 et seq. of this volume. 
* Page 87 of this volume. The paper here referred to was written subsequently to the reading 
of the manuscript of this essay, and this was also the case with the remarks in the text on determination 
of blood. 
