40 Richards . — The Evolution of 
equalized, being kept the while at the temperature of the 
cooler of the two potatoes, namely 24-1° C. It is evident from 
these experiments that while the conductivity of the tissue for 
heat may not be very rapid in comparison with other bodies, 
it is not to be disregarded. Hence it is not too much to say 
that the actual heat-reaction of the wound itself appears less 
localized than it in reality is. It is, of course, impossible to 
separate these two factors, the actual warmth and the con- 
ducted warmth ; but having found that, even including the 
latter, the tissue does not seem to show any increase in 
temperature beyond 20 m. from the wound, it is safe to say 
that the actual wound-reaction is probably considerably inside 
of even this. 
In the experiments with the two bell-glasses packed with 
cotton- wadding, the rise in temperature caused by a large mass 
of potatoes — 500-600 grams — may be plotted on a curve which 
has much the same course as that determined by the thermo- 
electric method (see Woodcut 2, p. 63). Naturally it is not 
possible to compare the actual temperatures indicated by the 
two methods, for neither is quantitative. It is to be expected 
that the rise indicated by a large mass of potatoes should be 
higher than that obtained from a single tuber, and such is the 
case. That, as measured by this method, it should be pro- 
portionally greater is not to be looked for ; as the indirect 
way of measuring the heat and the loss by radiation gives no 
accurate knowledge of the actual amount produced. The 
method is of value, however, in that in the two bell-glasses 
are two equal masses of potatoes under exactly similar con- 
ditions, except that in one they are injured while in the other 
they are normal. The rise to the maximum takes some twenty- 
four hours after the potatoes have been cut and returned to the 
bell-glass, and is about 0-9° C. higher than the temperature 
given by the uninjured potatoes, the latter showing ordinarily 
a plus temperature of 0-4° C. above that of the surrounding air. 
The return to zero of difference follows in the course of a few 
days. Such a method as this, if strictly followed out calori- 
metrically, would give results which could be better compared 
