180 C. M. CHILD 



On pages 564 to 568 of the paper on senescence (Child '11a) 

 the records of such a temperature series were given. Figure 2 is 

 a reproduction of figure 15 of that paper. The series (Series 

 140) was prepared as follows (Child '11a, pp. 565-6) : 



The worms used were 15-18 mm. in length and were well nourished 

 when collected (Nov. 25). They were kept in the laboratorj^ 24 days at 

 a temperature of 18°-22°C. without food, during which time they used 

 up most or all of their reserves. At the end of this period a stock of 

 about 100 worms was placed in dishes surrounded by running water at a 

 temperature of 8°-10°C. From this stock two sets of 10 worms each 

 were taken after 12 days, 22 days, 37 days and 65 days at the low tem- 

 perature. One of these sets in each case was placed in alcohol 1.5 per 

 cent at the same temperature, 8°-10°C., at which the worms had been 

 kept, the other in alcohol 1.5 per cent at room temperature, 18°-22°C. 



The two curves in figure 2 are plotted from these two lots of 

 forty worms each. Since each lot of forty worms is made up of 

 worms taken at different periods during sixty-five days, the 

 curves do not show the changes in resistance which occurred in 

 the stock during this period, but since these are the same at any 

 given time for all the worms of the stock, it is better for the pres- 

 ent purpose to eliminate them. The two curves then show simply 

 the effect of placing worms which had been kept in water at a 

 certain temperature, in alcohol at different temperatures. The 

 lower curve ac shows the resistance of the worms at the lower 

 temperature, the upper curve ah the resistance at the higher tem- 

 perature. As in figure 1, each small space of the cross section 

 paper along the axis of ordinates represents 2 per cent of the total 

 number of worms used, and each space along the axis of abscissae 

 represents one day. The curves show that the worms at the 

 higher temperature possessed greater resistance. 



In another similar series the stock was kept at room tempera- 

 ture, 18° to 22°C. and from this parallel lots were taken at inter- 

 vals, one lot in each case being placed in alcohol at 18° to 22°C., 

 the other in alcohol at 8° to 10°C. In this series, as in Series 140, 

 the worms in alcohol at the lower temperature always showed 

 less resistance than those at the higher. 



There can be no doubt, I think, that the difference in resistance 

 under these conditions is due to the difference in the rate of reac- 



