264 ON THE EARLY STAGES OF INFLAMMATION 
from its connexions was in an exceedingly delicate condition, and any agent used 
for arresting the action of the cilia was very apt to destroy at the same time 
the vitality of the cells. Thus when the object was warmed by placing the 
glass plate on a piece of iron at about 100° Fahr. for half a minute, the vibratory 
movements were arrested, but never recovered, and in a short time the cells 
swelled up by endosmose. It appeared probable that the tissue had suffered 
during the time required for the cooling of the glass: and in order to avoid 
this, and also prevent the object-glass becoming obscured by vapour from the 
warm water condensing upon it, the epithelium was placed between two slips of 
thin covering glass, kept from too close approximation by fragments of the 
same material interposed, the whole forming a layer so thin that it would be 
rapidly heated if any hot body were placed in its vicinity, and cooled as quickly 
on its removal. A small cautery iron, with a bulbous extremity about as big 
as a hazel-nut, just too hot to bear in contact with the finger, was now put 
behind the stage of the microscope, within about three-quarters of an inch of 
the object, the diaphragm plate having been removed to afford room for this 
being done without interfering with the light sent up by the reflector. The 
result, which I watched from the first, was the same that I had once before 
observed from the very gentle application of heat to a portion of a frog’s tongue, 
viz. primary increase in the action of the cilia which had previously been languid,* 
but which, within ten seconds of the approximation of the cautery, were moving 
with great rapidity, and continued to do so for about twenty-five seconds, at 
the expiration of which their motion was seen to be diminishing, and after 
another minute and a half it was considerably more languid than at the beginning 
of the experiment. The cautery being now removed was found to be much 
cooled though still warm, and its withdrawal did not affect the cilia, which still 
remained much in the same state after the lapse of eight minutes. I now 
repeated the experiment upon a fresh portion of epithelium, but this time used 
the cautery red hot, placing it about 2 inches behind the object : no sooner 
had this been done than the action of the cilia became excessively increased, 
but this did not continue for more than five seconds, when they became per- 
fectly motionless. The hot iron was now at once withdrawn, but the cilia 
under special observation did not recover. In other situations in the same 
specimen, however, movements were observed in the course of the following 
minute, and it was still continuing seven minutes later, when a part having 
‘ Professor Weber, of Leipsig, observed several years ago that the action of cilia upon epithelium 
cells removed from the human nostril was increased by gentle warmth, but retarded by cold. In that 
case the elevated temperature was natural to the tissue, and might be supposed to operate by restoring 
it to its normal conditions. In the cold-blooded reptile, however, the accelerated movement under 
the influence of heat has, of course, a very different significance. 
