Both kinds of phobias (or obsessions) often occur side by side, though the atypical phobias which depend on obsessions need not necessarily develop on the basis of anxiety neurosis. A very frequent, ostensibly complicated mechanism appears if the content of an original simple phobia of anxiety neurosis is substituted by another idea, the substitution is then subsequently added to the phobia. The “protective measures” originally employed in combatting the phobia are most frequently used as substitutions. Thus, for example, from the effort to provide oneself with counter evidence that one is not crazy, contrary to the assertion of the hypochondriacal phobia, there results a reasoning mania. The hesitations, doubts, and the many repetitions of the folie du doute originate from the justified doubt concerning the certainty of one’s own stream of thoughts, for, through the compulsive like idea one is surely conscious of so obstinate a disturbance, etc. It may therefore be claimed that many syndromes of compulsion neurosis, like folie du doute and similar ones, can clinically, if not notionally be attributed to anxiety neurosis.[43] 8. The digestive functions in anxiety neurosis are subject to very few but characteristic disturbances. Sensations like nausea and sickly feeling are not rare, and the symptom of inordinate appetite alone or with other congestions, may serve as a rudimentary attack of anxiety. As a chronic alteration analogous to the anxious expectations one finds a tendency to diarrhea which has occasioned the queerest diagnostic mistakes. If I am not mistaken it is this diarrhea to which Moebius[44] has recently called attention in a small article. I believe, moreover, that Peyer’s[45] reflex diarrhea which he attributes to a disease of the prostate is nothing other than the diarrhea of anxiety neurosis. The deceptive reflex relation is due to the fact that the same factors which are active in the origin of such prostatic affections also come into play in the etiology of anxiety neurosis. The behavior of the gastro-intestinal function in anxiety neurosis shows a sharp contrast to the influence of this same function in neurasthenia. Mixed cases often show the familiar “fluctuations between diarrhea and constipation.” The desire to urinate in anxiety neurosis is analogous to the diarrhea.