A CLINICAL STUDY ON HYDROA. 17
tion for the arms and legs, and is almost always accompanied by a similar eruption on the buccal mucous membrane. It is ushered in occasionally by slight malaise, anorexia, and some feverishness, and is characterized by little, rounded, defined papules, varying in size, which on the second day are capped by a clear vesicle rapidly becoming opaque, and the contents then dry into a crust. The dis- ease is made up of one or successive crops of the eruption, and there is a tendency to relapses. Although this description marks the main features of the disease, it will be seen later on that the details, cer- tainly of what he calls hydroa vesiculeux, are very different from those of the other two varieties. Bazin contended that though one extremity of the group, hydroa vesiculeux, bore a marked resem- blance to erythema papulatum, still the vesiculation distinguished it, inasmuch as it was a constant and essential part 0/ the disease, and not a mere accessory symptom as in some rare cases of erythema. It could not be placed with herpes, because the whole course, mode of evolution, and appearance of the disease were quite unlike anything seen in herpetic eruptions, as ordinarily understood. At the other end of the chain, hydroa buUeux was very difficult to distinguish from pemphigus ; but the small size of the bullae, the constant ter- mination in cure after from four to six months' duration, and the predilection for certain circumscribed regions, separated it from that disease.
Now, Bazin's hydroa, in my opinion, must be regarded as em- bracing, in the main, too little, although in one direction it includes too much. It includes the herpes iris of Willan and Bateman, a cir- cumstance which has not been sufficiently recognized by those who have dealt with this subject, and the ignorance of which fact has led to much confusion in the use of the term hydroa. The herpes iris of Willan and Bateman is perfectly distinct from the hydroa as I under- stand the latter disease, but with this exception Bazin's hydroa in- cludes too little, as stated above. The limits of his first variety (H. vesiculeux) are too narrow, and should include cases which possess a more decidedly herpetiform aspect ; or, rather, the hints are too abruptly given, since there are many cases which exhibit transitional stages or phases betwixt hydroa vesiculeux and a more or less general and scattered herpetiform eruption. Bazin's second variety, H. vacciniforme, was defined upon insufficient data, those of one case only, as it would seem, and the relations of which, in fact, had not been clinically traced out ; but in our experience it is a mere modification of H. bulleux. The third variety, H. bulleux, on the other hand, like the first, is defined within too narrow limits. Bazin thought it different from pemphigus entirely. No doubt the points of distinction are in the bulk of cases sufficient, but in some cases the differences are not so marked as to be decisive. Cases will be quoted in proof of' this point later on. It is likely that H. bulleux and many cases of so called pemphigus pruriginosus are identical in nature.
In France, the land of its birth, liydroa at the present time ap-
