124 



Scientific Proceedings (92). 



Fifteen different series of tests were conducted with this 

 apparatus during the years 1916, 1917 and 1918, 261 animals in 

 all being used. Young guinea pigs were selected, usually weighing 

 between 150 and 300 grams, and they were kept under the experi- 

 mental conditions for from 4 to 24 days, being weighed each day. 

 Food supply and other conditions were of course maintained 

 constant in the two compartments. 



The results for individual series were somewhat variable, but 

 in general it was evident that the animals exposed to the fecal 

 odor did not grow as fast for the first week as did the controls. 

 Later however they gained more rapidly and by the end of two 

 weeks had generally caught up. This relation appeared in 12 

 of the 15 series, while in the other 3 no initial check in growth rate 

 was observed. 



Calculating the ratio between the weight of the animals ex- 

 posed to the odor and the weight of the control animals for each 

 day of each series, and then averaging these ratios (which seems a 

 legitimate procedure under the conditions of the experiment) 

 we obtain the general averages tabulated below. 



Ratio of Per Cent. Gain of Guinea Pigs Subjected to Putrid Odors to Con- 

 trol Guinea Pigs, by Days. 



(Average of is Series.) 

 13 3 4 5 6 7 89 10 II 12 



— 10.5 —22.6 —26.8 —27.0 —14-5 —18.7 —20.1 —4.7 —7.6 —8.3 —5.6 —7.4 



13 14 15 

 — 2.2 —0.2 0 



These results would seem to indicate that the breathing of 

 putrid gases causes a real reduction in the rate of growth of guinea 

 pigs during the first week of exposure; but that this effect is a 

 transitory one, the exposed animals gradually becoming accus- 

 tomed to the odor and attaining after two weeks a normal weight. 



