101 



Table XXV. — Influence of retarded development upon sex. 



Mean av- 

 erage effec- 

 tive tem- 

 perature. 



Average time under 

 that temperature. 



Number 

 of males 

 produced. 



Number 

 of females 

 produced. 



Average total effective 

 temperature. 



Males. 



Females. 



Males. 



Females. 



° F. 

 18.4 

 19.5 

 23.0 

 23.0 

 23.0 



Days. 

 37.6 

 28.9 

 20.8 

 22.0 

 28.8 



Days. 

 34.0 

 28.6 

 19.8 

 22.2 

 25.9 



3 

 30 

 25 

 25 

 17 



18 

 22 

 33 

 25 

 10 



° F. 

 692 

 563 

 478 

 500 

 662 



° F. 

 625.0 

 563.0 

 455.0 

 511.0 

 596.0 



a 21. 4 



25.4 



a 25.1 



blOO 



&108 



a 548 



a 531. 3 



a Average. 



b Total. 



With lots 1 and 2 the temperature alternated from an average of 

 33.8° effective temperature during the daytime to an average of 3° 

 effective temperature at night. Number 1 became very diy, and 

 development was slightly delayed because of this fact. Among the 

 squares kept continuously at a low temperature, lot 5 was under test 

 for a larger portion of the developmental period than any other lot. 

 It is noticeable that in this case, in which the influence of the low tem- 

 perature was continued for the longest time, the largest proportion of 

 males was produced. As a whole, the table shows that there is a com- 

 paratively slight difference between the average of the total effective 

 temperature required for the development of males and that required 

 for females. A careful study of the table indicates that development 

 at a low temperature has some tendency to produce a larger proportion 

 of male than female weevils, and this is certainly the case in the late 

 autumn (see p. 14). 



LABORATORY EXPERIMENT IN EFFECT OF TEMPERATURE UPON 

 LOCOMOTIVE ACTIVITY. 



The experiments here given were performed by Dr. A. W. Morrill. 

 In the absence of apparatus especially designed for such work, use 

 was made of a very simple device, constructed as follows: 



A thermometer was passed through a cork and inclosed in a test tube, 

 which in turn was placed within a hydrometer cylinder of sufficient 

 depth to inclose it (PI. XVI, fig. 72). " 



Weevils were inclosed in the test tube with the thermometer, and 

 the temperature of the cylinder varied either by heating gently or by 

 the use of ice water. Starting with the thermometer at 61° F. the 10 

 weevils inclosed were found to move slowly, half of them being quiet. 

 As the temperature was gradually raised the activity of the weevils 

 increased up to 105° F. When the temperature reached 95° F., or 

 over, the weevils were running up and down the tube. By filling the 

 cylinder with cold water the temperature was lowered to 86° F., at 

 which point the weevils began to cluster at the top on the cork and 

 were crawling slowly. By the addition of ice in the cylinder the tem- 



