86 Gerald F. Hill: 



May, 1917, and continued during the folloAving June, Noveniber- 

 and December. Tlie insects in (iroup A were reared from pupae 

 in the laboratory, whilst those in Groups B and C were collected on 

 the liost. The ages of the " ticks " in Group B were judged only 

 from their appearance and size. In Group C the recjuired numlver- 

 of adults was selected from mated pairs. 



yafvre of Bcceptacles and the co?idifions under which the 

 ^'Ticl-s^' were kept. 



Erperiment No. 6. 



A sod of lawn grass in a Petri dish, with a glass chinjney 6.4 cms.: 

 high and 6.2 cms. wide, firmly embedded in the middle to form an 

 enclosure. The enclosed area was kept moist by water poui-ed on 

 the sod outside the cliimney. This receptacle was kept in a cellar- 

 under the Institute buildings. 



Experiment 'So. 7 . 



This receptacle was prepared in the same manner as No. 6, but 

 it was placed under a table on the lawn within tJie Institute quad- 

 rangle. 



Experiment No. 8. 



Soil in Petri dish, pressed down to form a level surface, upon, 

 which a few dry leaves were placed. Position as in No. 7. 



Experiment No. 9. 



Keceptable prepared as in No. 8, but placed in cellar, as in No. 

 6. 



Experiment No. 10. 



Prepared similarly to Nos. 8 and 9, excepting that no leaves M^ere 

 placed on the surface of the soil. The position was on the lawn, as- 

 in Nos. 7 and 8. 



Experiment No. 11. 



As in No. 10, but placed in cellar, as in Nos. 6 and 9. 



Experiment No. 12. 

 Sheep's wool (about one handful) placed in an open Petri dish on 

 labor atorv table. 



