148 L. B. NICE 



when other mice are running their highest and reaching its maxi- 

 mum at the thirty-fifth week when the activity of all the other 

 mice is decreasing. No. 9 and No. 12 belong to type 1 and both 

 exhibit great activity. No. 12 has a remarkably high record, 

 much higher than any of the other mice in the different lines of 

 the experiment. It exercised 169 per cent as much as the average 

 and 122 per cent as much as control No. 4, the second most active 

 of all the mice. 



The average total activity of these mice is almost equal to that 

 of the controls. 



None of these mice died. They gained 3.5 grams during the 

 experiment, which was less than half what the control mice gained. 

 The last month they showed an average loss of 1.5 grams. 



Nicotine did not seem to affect the health of these mice but 

 may have slightly checked their growth. 



Whether the wide variations in the activity of these mice 

 were caused by nicotine cannot be known without further experi- 

 ments. Nicotine may have had a stimulating effect on activity, 

 shown particularly in No. 12 with its remarkable record and in 

 No. 9. No. 10 would be an exception to such a theory. No. 11 

 might be explained as being naturally a very inactive mouse but 

 that the cumulative effects of nicotine stimulated him to activity. 

 Or it is possible that all these variations were due to chance. 



Caffeine lirie 



Three of the mice in this line have low records of total activity. 

 Nos. 13 and 15 run very low throughout the experiment. They 

 have the lowest records of total activity of all the mice used 

 in the experiment. No. 13 ran 54 per cent as much as the average 

 and 39 per cent as much as No. 4, the most active mouse in the 

 control line. No. 14 starts out well but soon decreases in activity 

 and dies when thirty- two weeks old. These three mice belong 

 to type 2. No. 16 belongs to type 1 and is above the average in 

 total activity. 



The average activity of these mice is the lowest of all the lines. 

 Their average maximum weekly run is only 93 932 revolutions 



