18 
CURT P. RICHTER 
the laboratory were not sufficient to obtain anything more than 
the very crudest gradations in temperature. 2 
Fig. 9. Distrubution of Spontaneous Activity with Relation to Time of 
Daily Feeding in a Low External Temperature 
Age of animals 200 to 300 days 
2 The attempts that were made to correlate activity with barometric pressure 
and humidity were not successful. It is very difficult to control these factors with¬ 
out an equipment especially adapted to this purpose. 
