9. In every test except grip and tapping, there is a marked increase in the variability of the gains after the second period. This is possibly due simply to the fact that the longer interval permits the intervention of more extraneous factors which may influence the scores in one direction or the other. 10. A group of 236 children with diseased tonsils showed equal distribution of I.Q. with a group of 294 children who were normal in this respect. CONCLUSIONS The article by MacPhail, which has been reviewed in a former chapter, showed pretty conclusively that the removal of adenoids and tonsils was followed by improvement in school work. That such improvement was not due to a rise in general intelligence can be concluded from the present experiment. That efficiency in school work does not rest wholly upon intelligence has been demonstrated more than once. The tendency here noted to improve in general physical tone may, perhaps, serve as a sign of the factor upon which such improvement depends. Improved health means better attention, better emotional response, greater resistance to fatigue, and probably increased efficiency. Interesting investigations of such improvement in efficiency might be made by administering educational tests to groups similar to those of the present study. The results of such an experiment would be exceedingly instructive, and would be more significant than conclusions drawn from school marks. By this means also we might determine along what special line efficiency is most affected. Since there was no recuperation in intelligence resulting from operation for adenoids and tonsils, it is reasonable to expect that there had been no retardation from which to recuperate. This supposition is borne out by results of the statistical study, wherein we found that a group of children suffering from diseased tonsils possessed equal intelligence with a group which was free from such defect. We can say to physicians, then, with fair amount of assurance, that removal of adenoids and tonsils will probably not raise to any great degree the intelligence level of the mentally defective child who is brought to him. We can say to students of the constancy of the I.Q., that it is not greatly lowered by adenoids and diseased tonsils and we may say to the clinical psychologist that these defects have no demonstrable effect upon general intelligence, whatever effects they may have on volitional and emotional normality,--the two elements which, along with intelligence are necessary for the maintenance of the individual as an instrument of social efficiency.