220 ON THE EARLY STAGES OF INFLAMMATION 
flows, become a source of movement in the blood and assist its flow through 
the capillaries; while others regard the heart as the sole cause of the circulation : 
and the difference of opinion on this fundamental point in physiology involves 
discordance in pathological theory, for some who hold the former view consider 
the changes which occur in the circulation at the commencement of inflamma- 
tion, to be principally owing to modifications of the ‘ vital’ moving force. 
The view that such a cause of movement exists, has been supported partly by 
argument drawn from the phenomena of inflammation: but these, as we shall 
see, require a very different interpretation. It has also been based upon a sup- 
posed analogy between the circulation of the blood in the higher animals and 
certain movements observed to occur without any visible source of mechanical 
power in tubes and cells in the vegetable kingdom, and, as was thought, also 
in some of the lower forms of animal life: but though a resemblance may pro- 
bably exist between some of these and the movements occurring in the processes 
of secretion and absorption and the circulation of nutrient fluid among the 
tissues of intercapillary spaces and non-vascular parts, the progress of modern 
discovery tends to show that the comparison is altogether inapplicable to the 
sanguiniferous system. It would, I think, be out of place to enter fully into 
this discussion on the present occasion, but my own experience with the frog 
leaves no doubt in my mind that in that animal contractions of the heart are 
the only cause of the circulation. I will content myself with mentioning two 
observations bearing upon this question. The first of these has reference to 
certain movements which occur for a considerable time after cessation of the 
heart’s action, and which, though of trivial and uncertain character, have had 
much stress laid upon them in this discussion. I have ascertained by observations 
made in several different cases, that they are produced by occasional spontaneous 
contractions and relaxations of the arteries. These changes in the calibre of 
the vessels continue, even in an amputated limb, for days after severance from 
the body :* I have repeatedly watched them taking place, and seen them give 
rise to the movement of the blood. 
The other fact to which I will allude appears to me to decide of itself the 
question at issue. Having occasion to examine, under chloroform, some very 
small frogs, measuring about an inch from the tip of the nose to the end of the 
coccyx, I found that the blood in the capillaries invariably flowed in a stream 
pulsating synchronously with the beats of the heart, which were visible through 
the parietes of the thorax; and however mildly the anaesthetic was adminis- 
* See Outlines of Pathology and Practice of Medicine, by W. P. Alison, M.D., F.R.S.E., &c., 1884, 
pp. 115 et seq. 
* See the preceding paper on the parts of the Nervous System which regulate the Contracticns of 
the Arteries, p. 27 of this volume. , 
