To the Editor:— I should like to be given the opportunity of replying to Dr. Novak's letter inThe Journaldated April 21. I agree with Hartman that the disintegration changes in the endometrium during the anovular cyclic hemorrhage of the macaque and during menstruation in the human female are almost identical. Probably in metropathia haemorrhagica the same process is also at work. So far as the macaque is concerned the disintegration changes seem to be the same whether the cycle is ovular or anovular and one is justified in assuming that the final cause of the bleeding is of a similar nature in these two cases and during menstruation in the human female. Robert Meyer and Schroder have suggested that the word "menstruation" should be restricted to the ovular cyclic bleeding and that the term "pseudomenstruation" should be used for anovular cyclic bleeding. The distinction may appear trivial, especially