Defect No. Examined % No. Examined % Defective vision 371 10.0 171 12.0 Defective hearing 49 1.4 29 2.0 _Defects of nose_ _54_ _1.5_ _21_ _1.5_ _Defects of throat_ _137_ _3.8_ _53_ _3.7_ Orthopedic defects 25 .7 25 1.8 Mentally defective 6 .1 80 5.6 Skin diseases 918 26.0 423 30.0 Miscellaneous 214 6.0 128 9.0 Total 1,774 49.0 930 65.0 It is evident from the majority of these investigations that there is some relationship between physical defects and pedagogical retardation. But whether or not the relationship is a causal one, they do not indicate. Simple co-existence of two characteristics is not necessarily significant that one is cause of the other. Plainly, though, if the removal of a physical defect is followed by improvement in the school progress, it may be argued that the presence of the defect was a causal factor in the previous retardation. The method in the few following studies, which seems to be employed to a greater degree than formerly, consists of measurement of such improvement. The Journal of Psycho-Asthenics, March and June, 1918, contains a paper on the "Results obtained from the Removal of Tonsils and Adenoids in the Feeble-minded," by Wm. J. G. Dawson, M. D. The author starts out rather discouragingly by regarding his hypothesis as an axiom. He says, "It is a well-known fact that hypertrophy of the tonsils and presence of adenoids may produce more or less dullness of the intellect in normal children. This is a result of the imperfect aeration of the blood which supplies the brain, on account of obstruction to respiration. In the Feeble-minded, conditions are more or less similar." One hundred and twelve cases in the Sonoma State Home, Eldridge, California, were operated on. Of these 6 are recorded as borderline, 39 as morons, 50 as imbeciles, and 17 as idiots. Adenoids were always removed when they were present. The results of the operation are as follows: Number Number before after Operation Operation