252 



Dr. G. Thin. 



fig. 1 there is represented what I believe to be an early stage, the 

 earliest which I have observed. A cluster of bacteria is seen on the 

 surface of the hair shaft, but under the cuticle of the hair, whilst on 

 the side of the hair others are seen embedded in granular debris, 

 probably remains of the inner root sheath. The shaft of the hair is 

 unbroken. 



In fig. 2 great numbers of bacteria are seen near the root of a 

 hair. By regulation of the fine adjustment the position of the 

 bacteria could be accurately made out. A considerable length of the 

 root sheath had come away with the hair, completely investing it. 

 The bacteria were found in a circular layer between the root sheath 

 and the shaft of the hair. They had neither penetrated the root 

 sheath nor the shaft. Fig. 4 indicates the position of the organisms 

 as they are seen when the centre of the hair is brought into focus : 

 the drawing being on too small a scale to show the individual bacteria 

 their position has been shown by dark shading. In fig. 5 the dark 

 shading shows the position of the bacteria when the lower surface of 

 the hair is brought into focus. By comparing these three figures with 

 each other, the arrangement of the bacteria becomes apparent. In 

 fig. 6 part of a hair is represented in which the removal of the sub- 

 stance of the hair shaft has shown a number of organisms disseminated 

 over the inner surface of the cuticle. They were traced towards the 

 thick unemptied part of the hair, in which they became lost in a thick 

 granular mass. In fig. 7 a hair is shown in which organisms were 

 found immediately under the cuticle. 



I infer from all these appearances that the bacterium penetrates 

 downwards between the internal root sheath and the shaft. Towards 

 the root of the hair it penetrates the hair substance, and as it multi- 

 plies it ascends upwards in the substance of the hair. The breaking 

 up, loosening, and disappearance of the hair is to be attributed to the 

 disorganisation of the hair substance by the growing organisms, for it 

 is impossible to suppose that a free development of bacteria could take 

 place in the shaft of a hair without the substance being decomposed 

 and its integrity destroyed, 



This is the inference which it seems to me follows naturally from 

 the detection of organisms in the diseased hairs in alopecia areata. It 

 might be alleged that it has not been shown that the composition of 

 the hair is not altered by some supposed error of nutrition, and that 

 bacteria find in these abnormal hairs a soil in which they can thrive. 

 No such alleged nutritive change has ever been shown to exist, and I 

 believe that the existence of an object of a definite size and form 

 having the characteristic appearance of a bacterium, and now ascer- 

 tained for a certain although a small number of cases, will afford to 

 workers in similar fields strong presumptive evidence that its presence 

 is the key to the mystery in which the disease has been shrouded. In 



