Coincidently with the rise in the amount of ketone bodies and with the corresponding fall in the alkaline reserves of the blood many observers have found a considerable fall in the percentage of blood sugar. Thus whereas in adults the blood sugar remains remarkably constant despite prolonged starvation, in children it would appear that there may be a considerable though sometimes shortlived fall and that in general the younger the child the more severe the fall. In a study of the metabolism of young children subjected to prolonged periods of fasting Shaw and Moriarty (3) found that the ketosis, the fall in the plasma bicarbonate and the hypoglyecemia were all on a much greater scale than in adult life. There was indeed a definite fall in the pH value of the blood. In the later days of the fast some degree of compensation was achieved and the sugar content became less depressed. The depletion of the glycogen reserves would appear to occur more rapidly in fasting children than in fasting adults and the body appears unable for some time to bring about a glucose synthesis sufficient to maintain a normal blood sugar.Upon children actually subject to cyclical vomiting as yet comparatively little work has been done. Hilliger (4) in 1914 first detected a fall from 0-14 to 0-07 in the blood sugar in a child with cyclical vomiting accompanying the development of the ketosis. In a young child two and a half years old, the subject of typical attacks of cyclical vomiting, Ross, Hughes and Josephs i6) found a fall in the blood sugar and of the C02 combining power of the blood, but noted that the recovery was so rapid that the hypoglyemmia could only be demonstrated during the height of the attack.