interruptus_, undischarged excitement and sexual abstinence, and in the latter, excessive masturbation and too numerous nocturnal emissions. In a few specially instructive cases, which had shown a surprising alternation in the clinical picture from one type to the other, it was possible to prove that there had been a corresponding change in the underlying sexual _régime_. If it was possible to put an end to the abuse and allow its place to be taken by normal sexual activity, a striking improvement in the condition was the reward. I was thus led into regarding the neuroses as being without exception disturbances of the sexual function, the so-called “actual” neuroses being the direct toxic expression of such disturbances and the psycho-neuroses their mental expression. My conscience as a physician felt pleased at my having arrived at this conclusion. I hoped that I had filled up a gap in medical science, which, in dealing with a function of such great biological importance, had failed to take into account any injuries beyond those caused by infection or by gross anatomical lesions. The standpoint of medicine was, moreover, favored by the view that sexuality was not something purely mental. It had a somatic side as well, and it was possible to assign special chemical processes to it and to attribute sexual excitement to the presence of some particular, though at present unknown, substance. There must also have been some good reason why the true spontaneous neuroses resembled no group of diseases more closely than the phenomena of intoxication and abstinence, which are produced by the administration or privation of certain toxic substances, or than Basedow’s disease, which is known to depend upon the product of the thyroid gland. Since that time I have had no opportunity of returning to the investigation of the actual neuroses; nor has this part of my work been continued by anyone else. If I look back today at my early findings, they strike me as being the first rough outlines of what is probably a far more complicated subject. But on the whole they seem to me still to hold good. I should have been very glad if I had been able, later on, to make a psychoanalytical examination of some more cases of simple juvenile neurasthenia, but unluckily the occasion did not arise. To avoid misconceptions, I should like to make it clear that I am far from denying the existence of mental conflicts and of neurotic complexes in neurasthenia. All that I am asserting is that the symptoms of these patients are not mentally determined or removable by analysis, but that they must be regarded as direct toxic consequences of disturbed sexual chemical processes.