During that period, some of those children suffered severely from scarlet fever, which, as a new disease, took a severe form in Japan, and the desquamation, or skin-peeling, was unusually severe, so that in those cases the test was a severe one. On several occasions I have called attention to the possibility of severe desquamation being followed by some change of patterns, and I still think this subject merits the attention of medical men, but no actual fact illustrating the apparent danger has yet been brought under notice. This may, however, be simply the result of a high degree of inattention to a subject which medical men do not seem to have interested themselves in until very recently. In acromegaly, a disease in which the fingers take on gigantic features, one might expect to find a very notable change of patterns, perhaps the addition of fresh lineations, but after some attempts to collect information not one single example of the kind has yet reached me. Besides testing growing children in the manner I have stated, many Japanese medical students between the ages of twenty and thirty were made use of in this way. The ridges were carefully shaved by razors, or smoothed away by sand-paper, emery dust, or pumice stone, so that no distinct patterns could be traced. The same tests were applied to my own fingers and to those of one or two medical friends who were quite sceptical as to the continuity of the patterns. Many of the patients at the hospital, or out-door dispensary, were also induced to submit, but not a single instance of variation in the patterns was ever brought to light. My own fingerprints have not varied since that date, a period of fully thirty years. However smooth the surface had been made, the old design came up again with perfect fidelity, yielding exactly the same imprints as before, subject only to those very minor variations already described in a previous chapter, to which even engravings are subject. Up to the period of my final return to England in 1887, a period of nearly nine years, enthusiastic and vigilant observation of this point gave me complete confidence in the permanence of finger-print patterns as a basis of personal identification. With the exception of acromegaly and skin-peeling after acute fevers, I can conceive of no biological reason why changes might be anticipated in those patterns, and up to the present no evidence has reached me that even those conditions do effect pattern changes. In old age the ridges shrink somewhat, and wrinkles here and there betray the drying up of tissues, which facts are revealed in printed impressions by fine white lines, often cutting across the lineations, not unlike those which occur in box-wood engravings, where hair-like lines betray some cleavage of the wood. In such a case the value of the pattern is not affected as a proof of identity. One may go beyond that, and say that, if after a lapse of forty years or so the old pattern is now crossed