34 MAL-NUTRITION 



of such observations, if they are not made with due regard to 

 the needs of the statistician.' To carry out these purposes, it 

 was necessary to emphasize every point where there was 

 defect in the data discussed. And these purposes have 

 been fulfilled, as the many inquiries made by school medical 

 officers to the Laboratory as a result of the memoir demon- 

 strate. That .Mr. Yule should find my emphasis of defect 

 in the data sufficient to discredit the memoir only indicates 

 how Httle he understood its purposes — he could hardly have 

 read its opening paragraph. 



But beyond and apart from these defects in the data, 

 upon which I purposely laid stress, Mr. Yule's criticisms 

 have wholly failed to convince me that there exists any 

 environmental condition producing an effect on the mentality 

 of the child comparable with that of heredity. Mr. Yule 

 cites Dr. Warner's result, that poor mentality arises from ill- 

 nutrition — nearly all modern medical experience shows it to 

 be essentially a congenital character, not the product of ill- 

 nutrition. I cannot accept, in view of what I know to the 

 contrary, Mr. Yule's sweeping condemnations of the untrust- 

 worthiness of the teacher's judgement, and I think it far 

 more probable that my low correlations of environment and 

 intelligence are due to the fact that the intelligence is not 

 a product — except indirectly through the heredity factor — 

 of environment, than to the hypothesis that the teachers' 

 judgements were ' of no value for any serious purpose '.^ 

 Those w^ho assert that intelligence is a product of nutrition 

 should certainly set to work and produce more reliable data 

 than those of Dr. Warner, and apply to them more satisfac- 

 tory statistical methods than those adopted by Mr. Yule. 



' Yule, School Hygiene, vol. i, p. 475. 



