H.—3l.

(b) According to Age, Blood undifferentiated.

Maori Susceptibility to Hydatid Disease. The intradermal test for hydatid disease introduced by Casoni is of diagnostic value. Dew states that in uncomplicated cysts an immediate reaction and delayed phase are obtained in 90 to 95 per cent, of cases. A percentage (40 per cent, in one investigation) giving an immediate wheal fail to show evidence of hydatid on detailed investigation. A negative reaction is highly important. In this investigation 0-25 c.cm. of standardized sterile hydatid fluid was injected into the dermal layer of the skin, a similar injection of normal saline solution serving as a control. Results were read after twenty minutes and again at twenty-four hours. Maori school-children's susceptibility to hydatid disease, as revealed by the Casoni test, is as follows :—

(a) According to Racial Purity, Ages mixed.

(b) According to Age, Blood undifferentiated.

Diphtheria Susceptibility of Maori. To ascertain the Maori's susceptibility to diphtheria the Schick test was used : 0-2 c.cm. of diluted diphtheria toxin was injected into the skin on the test forearm, while a similar dose of heated toxin acted as control on the other arm, results being read twenty-four hours later, and again at varying times from the third to the sixth day according to the exigencies of one's programme. Pseudo-positive and pseudo-negative reaction were respectively included in positive and negative results. The susceptibility of white children varies greatly. In Aberdeen burgh and county over eight thousand school-children when tested gave nearly 70 per cent, positives. In Great Britain the general population (mainly children under fifteen) susceptibility to diphtheria approximates 69 per cent. In Belgium Schick tests revealed 75 to 59 per cent, susceptible under five years, 48 to 42 per cent, susceptible from five to ten years, and 39 to 44 per cent, susceptible from ten to fifteen years. In Australia, in one district, 31-5 per cent, of children were susceptible. In New Zealand, in an isolated district, about 80 per cent, of children gave positive tests. The susceptibility of coloured races seems less. Of 1,859 Sudanese school-children 17-21 per cent, were Schick positive. Of 183 Indian children tested 23-1 per cent, were positive. The Maori susceptibility is as follows : —

(a) According to Purity of Blood, Ages mixed.

37

Ages, in Years .. .. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. Von Pirquet positives .. 13 34 36 35 37 47 32 60 41 17 8 2 Number tested .. .. 184 244 259 238 243 213 184 218 153 82 29 7 Positives, as percentage .. 7-06 13-93 13-89 14-70 15-22 22-06 17-39 27-52 26-79 20-73 27-58 28-57 i ; . ___________________

Full-blooded Three-quarter Half Maori Quarter Maori Maori. Maori Blood. Blood. Blood. Casoni positives .. .. .. .. 165 47 49 9 Number examined .. .. .. 1,277 413 283 81 Expressed as percentage .. .. .. 12-92 11-38 17-31 11-11 I

Ages, in Years .. ..5. 6. 7. 8. 9. I 10. 11. 12. 13. 14. 15. 16. Casoni positives .. .. 29 29 45 37 26 22 20 28 20 11 2 1 Expressed as percentage .. 15-76 11-88 17-37 15-54 10-69 10-32 10-86 12-84 13-07 13-41 6-89 14-28 ,

Full-blooded Three-quarter „ ,,,» . m , Quarter Maori Maori. Maori Blood. Half Maori Blood. BIood Schick positives ...... 122 46 67 20 Number examined .. .. 1,277 413 283 81 Expressed as percentage .. .. 9-55 11-13 23-67 24-69