On Bacterium decalvans. 



253 



extracting hairs for examination I took them from a considerable 

 breadth of margin, and as the proportion of the hairs examined 

 which showed any change or evidence of organisms was small, it is 

 probable that these are present only in a narrow zone, and that after a 

 hair is once attacked development takes place rapidly and the hair soon 

 falls. 



It may be well to divide the statements made in this paper into two 

 heads ; those which relate to ascertained facts, and those which relate 

 to a theory of the causation of alopecia areata, which I believe is 

 sustained by these facts : — 



1 . The facts are that minute bodies of definite and fixed shape and 

 size are found in and on the hairs in alopecia areata. These bodies 

 are distinct from the granular elements present in hairs, and are 

 neither oily particles nor crystals. They are of the size and shape, 

 and have the refractive qualities of bacteria. When present in small 

 numbers on the shaft the hair is entire, whilst within some hairs much 

 affected by the disease they were found in great numbers. 



2. The theory is that these bodies are bacteria, and that the 

 disappearance of the hair is due to a breaking up of the hair shaft by 

 the multiplication in it of the organisms. 



As I believe it is desirable to give to definite objects like those 

 which I have described a name which will mark their association with 

 the theory I have founded on them, and as I am myself satisfied as to 

 their nature, I suggest the term Bacterium decalvans as a convenient 

 designation. 



DESCRIPTION OF PLATE 3. 



Figure 1. Case of S. B. A small group of organisms on the shaft of the hair, under 

 the cuticle. Others are seen scattered in a granular mass which is 

 adherent to the hair. 



(Camera drawing.) x 600. 

 Figure 2. Case of I. F. Organisms between the root-sheath and the shaft of the 

 hair near the root. (Drawn by Mr. Noble Smith.) 

 x about 470. 



Figure 3. Organisms from the group shown in fig. 2, more highly magnified. 



(Camera drawing.) x 560. 

 Figure 4. The hair shown in fig. 2, the focus being now in the axis of the hair. 



The position of the organisms is indicated by the dark shading. 

 Figure 5. The hair shown in fig. 2 when the focus is carried down to the under 



surface, the position of the organisms being again indicated by the dark 



shading. 



Figure 6. Case of S. B. In a part of the hair from which the substance of the 

 hair-shaft has disappeared and the cuticle left empty, organisms are seen 

 lying on the internal surface of the cuticle. 

 (Camera drawing.) x 880. 

 Figure 7. Case of N. S. Organisms on the shaft and be r •th the cuticle. 

 (Camera drawing.) 



