Bacillus acidophilus has been used successfully in the treatment of constipation and diarrhea.1 However, it would be difficult to state precisely how successful a therapeutic agent it is. Neither of the intestinal conditions dealt with—constipation and diarrhea—permit exact definition; consequently, the interpretation of results must be somewhat arbitrary. For this reason, if no other, it would seem desirable that investigators in this field present their facts as objectively as possible. Obviously, there are many factors which must be considered. The necessity for keeping a careful record of the frequency and character of defecations is well recognized. The dosage of B. acidophilus preparations is always of importance, but unfortunately it is unstandardized and therefore at present has little significance. Thus 10 c.c. of B. acidophilus milk containing 20,000,000 viable organisms per cubic centimeter in the hands of one clinician is unquestionably more desirable than 1,000 c.c. containing 10,000 viable organisms per