The pH of the mouth in the newborn infant.

inrdction In an article on vaginal thrush, Liston and Cruickshank (1940) state that ' the organism finds an acid moist smuface on which to grow in two situations-the mouths of suckling infants or invalids and the vagie of adult women in certain circmnstances.' Further, they ' attach great importance to the pH reaction as a factor influencing the possibility of infection with Oidium albicans.' Confining their attention to the question of vaginal thrush, they offer no evidence in support of the statement that the mouth of the sukling infant provides an acid moist surface, and no pH observations are given. Published information with regard to the pH of the mouth of the newborn appears larly scarce, the only referce the writer has foumd being that of Allaria(1907). Here it is stated that 'the reaction of the mouth in thenewborn infant is neutral or slightly acid to litmus and in the nursling continues to react acid to litmus but does not turn methylpH orange. The pH is very slightlY on the acid 7-0 or the alkaline side, or indeed exactly at the neutral point (7 0), provided freshly secreted 6-E saliva is taken. After it remains in the mouth for a while it becomes distinctly acid.' 6 In view of the importance which Liston and Cruickshank attach to this aspect of the 6soil upon which the Oidium albicans flourishes so commonly, and because of the lack of 6-2 readily available data, it seems desirable that some observations should be recorded. 6-0