TOXICITY OF BARIUM CARBONATE TO RATS. 7 



The results obtained from feeding both poisoned and unpoisoned 

 food are summarized in Tables 8 and 9. The rats were divided 

 arbitrarily into weight groups, and the food intake calculated on the 

 per rat and the per kilo basis. The probable errors are given for 

 individual observations as well as for each group. 



Table 8. — Intake of control food (rats divided into weight groups). 





Num- 

 ber 

 rats. 



Weight. 



Amount eaten. 



Probable error. 



Amount 



eaten 



per 



kilo. 



Probable error. 



Weight group. 



Total. 



Aver- 

 age. 



Total. 



Aver- 

 age. 



Single. 



Series. 



Single. 



Series. 



Grams. 

 140 to 199 



14 

 19 



Grams. 

 2,418 

 4,430 



Grams. 

 173 

 233 



Grams. 

 32.0 

 49.35 



Grams. 

 2.29 

 2.59 



±0.79 

 ±0.48 



±0.21 

 ±0.11 



G^ams. 

 13.2 

 11.1 



±4.6 

 ±2.1 



±1.23 



200 to 249 



±0.49 



250 to 299 



15 



8 



4,094 

 3,166 



273 

 396 



57.45 

 11.6 



3.83 

 1.45 







14.03 

 3.50 







300 up 



















Total for 250 

 up 



Total for all 



experiments 



23 



56 



7,260 

 14,108 



316 

 252 



69.05 



150.4 



3.00 

 2.7 



±0.7S 



±0.15 



9.51 

 10.65 



±2.5 



±0.51 









Table 9. — Intake of food containing barium carbonate, all percentages (rats divided into 



weight groups). 





No. 

 rats. 



Weight. 



Amount eaten. 



Probable error. 



Amount 



eaten 



per 



kilo. 



Probable error. 



Weight group. 



Total. 



Aver- 

 age. 



Total. 



Aver- 

 age. 



Single. 



Series. 



Single. 



Series. 



Grams. 

 140 to 199 



22 

 26 

 17 

 14 



Grams. 

 3,791 

 5,703 

 4, 614 

 4,795 



Grams. 

 172 

 220 

 271 

 342 



Grams. 

 56.6 

 68.5 

 44.65 

 35.8 



Grams. 

 2.57 

 2.64 

 2.62 

 2.56 



±0.65 

 ±1.3 

 ±1.0 

 ±0.79 



±0.15 

 ±0.26 

 ±0.25 

 ±0.21 



Grams. 

 14.9 

 12.0 

 9.7 



7.5 



±3.88 

 ±5.92 

 ±3.72 

 ±2.30 



±0.86 

 ±1.12 

 ±0.90 

 ±0.62 



200to249 



250 to 299 



300 up 





Total 



79 



18,903 



239 



205. 55 



2.60 







10. 85 















Slightly greater variations occurred in the control series, and 

 would seem to indicate the need of caution in too strict a mathemat- 

 ical interpretation. The data indicate, however, that on the average 

 the food intake was approximately one one-hundredth of the rat's 

 weight, both for the control and the barium-carbonate-fed series, 

 from which it was concluded that the barium carbonate added to 

 the diet was perfectly palatable. Just why the food intake per rat 

 for all of the groups is approximately the same, when the stomachs 

 of larger rats have greater capacity, is not at present clear. The 

 greater food intake per kilo for the smaller rats is, under these cir- 

 cumstances, without significance. 



For practical purposes, however, the individual food intake is the 

 most important (Table 7) , since the rats which eat scantily are the 

 ones which necessarily determine the percentage to be placed in the 

 diet, because they must also ingest a lethal dose. With this object 



