“A blackish ooze takes place in some hysterical cases. More striking is the class of cases in which the colouring matter is derived, like the bright colours in the plumage of parrots, from copper, and in some cases from iron. Workers in copper have been found subject to it. The sweat is generally of a bluish colour in those cases. Red sweat has been observed in lockjaw. A kind of saffron colour I have found to be not very uncommon in some classes of malarious cases. One lady I attended had an extraordinary temperature during some of the attacks, the thermometer recording 110° Fahrenheit. With a temperature of about 104° Fahr. she did not seem to be really unwell. I took good impressions at one of those times, with the yellow-coloured sweat. Ordinarily, however, sweat does not help, but hinder, impressions from being made. A case of blue sweat came under my treatment quite recently. There was no history of copper poisoning.” Since writing the above, I have met with other cases of coloured sweat. My teacher, the late Sir Thomas McCall Anderson, in his work, _Contributions to Clinical Medicine_, mentions some very interesting facts in this connection in the chapter on “Hemidrosis.” Herbert Spencer, in the May number of the _Nineteenth Century_ (1886), discussing the Factors of Organic Evolution, explains the origin of the ridges in a passage which I must quote in full:-- “Continuous pressure on any portion of the surface causes absorption, while intermittent pressure causes growth: the one impeding circulation and the passage of plasma from the capillaries into the tissues, and the other aiding both. There are yet further mechanically produced effects. That the general character of the ribbed skin on the under-surfaces of the feet and inside of the hands, is directly due to friction and intermitten pressure, we have the proofs: first, that the tracks most exposed to rough usage are the most ribbed; second, that the insides of hands subject to unusual amounts of rough usage, as those of sailors, are strongly ribbed all over; and third, that in hands which are very little used, the parts commonly ribbed become quite smooth.” CHAPTER III FINGER-PRINT PATTERNS Before reading this chapter, let the reader carefully examine the clear lineations shown so well in the photographic picture of the Zebra’s stripes, opposite. They will be found to resemble very closely the lineations on the skin of human fingers, as printed when enlarged by photography, forming very similar patterns. Similar linings occur in the hide of the tiger. [Illustration: GREVY’S ZEBRA.--Showing Lineations like Finger-Print Patterns.] [Photo. Pictorial Agency]