MATERIALS FROM PLANTS AND ANIMALS 423 



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 Measure 



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 Capacity 



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Fig. 173. Relation of smoking to physical growth 



The first column shows the average advantage of non-smokers (indicated by white 

 space) over occasional smokers (indicated by shaded space). The second column 

 shows the average advantage of non-smokers over regular smokers. It is not at all 

 likely that the smaller, lighter, weaker boys were the ones to take up smoking in 

 larger proportions. The differences shown by these records must be, at least in large 

 part, due to smoking. These measurements are from the physical-training depart- 

 ment of Yale University 



blood. Whether tobacco is injurious as ordinarily used cannot be known 

 for all people, since there is a great deal of variation as to how we react 

 to it. Apparently adults can stand more of it than young people ; some 

 can stand a great deal ; some none at all. Most of us could probably get 

 used to it if we made the effort. It is questionable, however, whether 

 those who are in the habit of using tobacco are helped as much as they 

 think or injured as much as its opponents think. Harmless enjoyment 

 



5 10 15 20 25 30 35 40 45 50 55 GO 65 70 75 80 85 90 95 100$J 



Fig. 174. Smoking and school standing 



The school grades of four groups of Illinois high-school boys (two hundred and one 

 in all). The numbers in parentheses give the number of boys in the group. The 

 forty-five who left school during the year were habitual smokers. Twenty-four of the 

 boys had learned to smoke but had given up the practice. The average grade of the 

 ten highest smokers w^as 78.9 per cent. The average of the ten highest in the school 

 was 90.9 per cent; none of these smoked. We cannot assume that the grade dift'er- 

 ences between smokers and non-smokers are due entirely to the fact of smoking. It 

 is likely that the more scholarly boys do not take to smoking as much as the others. 

 If none of the boys smoked, some of those with poor scholarship would nevertheless 



still be in the low-scholarship groups 



