In a recent _brochure_ on the "Rhythm of the Pulse"[373] I showed _inter alia_ that the readings of the pulse, in both man and woman, if arranged in lunar monthly periods, and averaged over several years, displayed a clear, and sometimes very strongly marked and symmetrical, rhythm.[374] After pointing out that, in at any rate some cases, the male and female pulse-curves, both monthly and annual, seemed to be converse to one another, I added: "It is difficult to ignore the suggestion that in this tracing of the monthly rhythm of the pulse we have a history of the monthly function in women; and that, if so, the tracing of the male pulse may eventually afford us some help in discovering a corresponding monthly period in men: the existence of which has been suggested by Mr. Havelock Ellis and Professor Stanley Hall, among other writers. Certainly the mere fact that we can trace a clear monthly rhythm in man's pulse seems to point strongly to the existence of a monthly physiological period in him also." Obviously, however, it is only indirectly and by inference that we can argue from a monthly rhythm of the pulse in men to a male sexual periodicity; but I am now able to adduce more direct evidence that will fairly demonstrate the existence of a sexual periodicity in men. We will start from the fact that celibacy is profoundly unnatural, and is, therefore, a physical--as well as an emotional and intellectual--abnormality. This being so, it is entirety in accord with all that we know of physiology that, when relief to the sexual secretory system by Nature's means is denied, and when, in consequence, a certain degree of tension or pressure has been attained, the system should relieve itself by a spontaneous discharge--such discharge being, of course, in the strict sense of the term, pathological, since it would never occur in any animal that followed the strict law of its physical being without any regard to other and higher laws of concern for its fellows. Notoriously, that which we should have anticipated _a priori_ actually occurs; for any unmarried man, who lives in strict chastity, periodically experiences, while sleeping, a loss of seminal fluid--such phenomena being popularly referred to as _wet dreams_.[375] During some eight or ten years I have carefully recorded the occurrence of such discharges as I have experienced myself, and I have now accumulated sufficient data to justify an attempt to formulate some provisional conclusions.[376]