20 MAL-NUTRITION AND THE TEACHER'S 



was undertaken ' because the assumption had been made 

 that certain types of deformity are the correlates of feeble- 

 mindedness. This assumption is so generally current that 

 it is made a principle of diagnosis '. 



The investigation was carried out in a most thorough 

 manner. Instead of relying on a mere impression of 

 ' defect ' of palate, the authors took a cast of the palates of 

 1,010 inmates of schools for the feeble-minded and of 614 

 normal individuals, the technique of the casting process 

 having been developed in dentistry. Every precaution was 

 taken to ensure accuracy. A preliminary examination was 

 made of the growth factor, and the methods of examination 

 were standardized by repeated measurement of the same 

 casts. Four measurements were discussed in their report. 

 These were: (a) The minimum distance between the first 

 molars, measured horizontally, from the bases of the 

 molars ; (d) the maximum height of the palate, measured 

 from the approximate plane of the gum line ; (c) the dis- 

 tance from the line connecting the two first molars to the 

 alveolar point ; (d) the distance between the canines, 

 measured horizontally from their bases. 



In Table III there is given a list of the means and 

 standard deviations of these four measurements among the 

 normal children and the feeble-minded for ages 6-13 ^ and 

 over 20, together with the probable errors ^ of the differ- 

 ences. The maximum difference between these means is 

 1.25 + -14 mm., while a large number of the differences are 



and Clark Wissler, Ph.D. American Journal of Insanity^ vol. Ixi, no. 4, 

 1905, p. 687. 



^ In the extreme cases, I tested the effect of basing the means on a standard 

 age distribution as shown in Eugenics Memoir VIII, p. 32, but found that the 

 differences were not significant. 



' The probable errors in Channing and Wissler's paper were calculated 

 from the formula a/ ^^ instead of from the usual -67449 a/^i- I have used 

 the latter. 



