1SS 



FRANCIS MARSH BALDWIN 



moist earth. Strips of black cloth were then tacked to a frame 

 around the margin of the board, making a dark box to include 

 the plates. Holes were cut in the cloth on either side for obser- 

 vation, a flap of cloth serving as a cover to the hole when not 

 in use. Within were placed four 1-c.p. electric bulbs (two on 

 either side of the glass) which were controlled by switches. 



Large subjects of Lumbricus terrestris were used throughout 

 the observations (four in the first series, and five in all the others) . 

 They were placed, one at a time, upon the surface above the 

 plates and allowed to burrow into the soil beneath (between the 

 plates), where their subsequent activity could be followed. The 

 soil was kept moist by occasional sprinkling. 



In preliminary observations, records were taken at 20-minute 

 intervals, at various times of day and night throughout the period 

 of one month. From data thus accumulated, the activity of 

 the four subjects is summarized (in minutes) in table I, which 

 indicates that the worms were active about one-third of the 

 entire time with a fairly wide individual variation. 



TABLE I 



Records of the activity of five subjects were subsequently 

 made on two different days (about a week apart), the obser- 

 vations being continuous for each of twenty-four hours. Table 

 II displays the results for the two days (a and b), giving "active" 

 times in minutes, by quarter-days. 



Although moderate individual differences in amount of activity 

 again appear, the average active time, when compared with the 

 total time of observation (1,440 min. for the whole day) closely 

 approximates that shown in table I. It is further to be noted 

 that the period of greatest activity, with but two exceptions 

 (I-a and Ill-b), falls within the hours 6-12 P. M. 



