428 M. H. JACOBS 



vessel of water which is kept at the final temperature. In this 

 case, the rise is at first rapid, becoming progressively slower and 

 slower — being represented, in fact, by the logarithmic curve of 

 Newton's well-known 'law of cooling bodies,' except that the 

 temperature in this case is increasing instead of decreasing. 



Of the three methods mentioned, the third is generally unde- 

 sirable, partly because of the greater difficulty of making allow- 

 ance for a constantly changing rate of temperature increase, 

 partly on account of the difficulty of determining the exact time 

 when the desired temperature has been reached, and chiefly 

 because of the great length of exposure (due to the slow rate of 

 change as the end point is approached) to temperatures whose 

 effects are almost as great as those of the one finally attained. 

 Method 1, in exact work, is applicable only to very small organ- 

 isms, since any attempt to apply it to large ones results in secur- 

 ing essentially the effects of method 3, with the additional disad- 

 vantage that on account of the slow conduction of heat, different 

 parts of the body reach the final temperature at different times. 

 Method 2, therefore, which involves raising the temperature at 

 a known rate until the desired point has been reached, is the most 

 suitable one for all except very small organisms and has been most 

 frequently employed. But in the past very little effort has been 

 made to take into account the influence on the final result of the 

 rate at which the temperature is raised. That this factor is 

 probably of importance is obvious, but to predict in advance in 

 what direction and to what extent it will operate is not always 

 an easy matter. 



Suppose, for example, that in a certain experiment a lot of 

 organisms are brought in the course of ten minutes from room 

 temperature to 40°C. and kept at the latter point until death 

 occurs. Would the time required to cause death at 40° be 

 greater, or less, if in another similar experiment the preliminary 

 rise were allowed to occupy thirty minutes instead of ten? It 

 might be argued, on the one. hand, that the slower rate would 

 be less favorable to the organisms than the rapid one because of 

 the greater length of exposure to temperatures below 40°, but 

 still sufficiently high to produce in the aggregate considerable 



