It will be observed that the composite of 56 female faces is made by the blending of two other composites, both of which are given.  The history was this—­I took the 56 portraits and sorted them into two groups; in the first of these were 20 portraits that showed a tendency to thin features, in the other group there were 36 that showed a tendency to thickened features.  I made composites of each of them as shown in the Plate.  Now it will be remarked that, notwithstanding the attempt to make two contrasted groups, the number of mediocre cases was so great that the composities of the two groups are much alike.  If I had divided the 56 into two haphazard groups, the results would have been closely alike, as I know from abundant experience of the kind.  The co-composite of the two will be observed to have an intermediate expression.  The test and measure of statistical truth lies in the degree of accordance between results obtained from different batches of instances of the same generic class.  It will be gathered from these instances that composite portraiture may attain statistical constancy, within limits not easily distinguished by the eye, after some 30 haphazard portraits of the same class have been combined.  This at least has been my experience thus far.

The two faces illustrative of the same type of tubercular disease are very striking; the uppermost is photographically interesting as a case of predominance of one peculiarity, happily of no harm to the effect of the ideal wan face.  It is that one of the patients had a sharply-checked black and white scarf, whose pattern has asserted itself unduly in the composite.  In such cases I ought to throw the too clearly defined picture a little out of focus.  The way in which the varying brightness of different pictures is reduced to a uniform standard of illumination is described in the Appendix.

It must be clearly understood that these portraits do not profess to give the whole story of the physiognomy of phthisis.  I have not room to give illustrations of other types—­namely, that with coarse and blunted features, or the strumous one, nor any of the intermediates.  These have been discussed chiefly by Dr. Mahomed in the memoir alluded to above.

In the large experience I have had of sorting photographs, literally by the thousand, while making experiments with composites, I have been struck by certain general impressions.  The consumptive patients consisted of many hundred cases, including a considerable proportion of very ignoble specimens of humanity.  Some were scrofulous and misshapen, or suffered from various loathsome forms of inherited disease; most were ill nourished.  Nevertheless, in studying their portraits the pathetic interest prevailed, and I returned day after day to my tedious work of classification, with a liking for my materials.  It was quite otherwise with the criminals.  I did not adequately appreciate the degradation of their expressions for some time; at last the sense of it took firm hold of me, and I cannot now handle the portraits without overcoming by an effort the aversion they suggest.