In the preceding paper1 are presented the results of a study of the succession of the protozoan fauna of a series of hay infusions. The present paper gives the results of some chemical investigations on the infusions employed by ProfessorWoodruff with a view to correlating, if possible, certain chemical conditions with the protozoan sequence there shown to occur.
Although oze cannot hope to obtain a complete analysis of the chemical factors involved, there are a limited number of determinations which can be made with some degree of ease and accuracy, and which may quite reasonably be expected to throw light upon this problem. In the present work a preliminary survey was made to determine those estimations which would be likely to yield satisfactory results, with the view of instituting an intensive study of such factors. The determinations2 thus first made were : (1) Phenolphthalein acidity, (2) Methyl-orange alkalinity, (3) Oxygen consumed, (4) Chlorides, and ( 5 ) Solids (total, organic and inorganic).
The ' phenolphthsjlein ~cidity' was gbtrtincd b j r titrsitiilg 5 w.
of infusion with 0.01 N NaOH, using phenolphthalein as indicator.
'L. L. Woodruff: Jour. Exp. Zool., vol. 12, No. 2. The present work was undertaken at the suggestion of Professor Woodruff, t o whom I am indebted for suggestions and criticism.