On Bacterium decalvans. 



251 



particles were present to such an extent as frequently to make accu- 

 rate observations impossible. 



In some hairs, however, this mode of preparation had produced 

 results which were most instructive. 



The effect of the potash and other treatment had been to get quit 

 of the whole contents of the cuticle at some parts, the cuticle being- 

 then seen as a transparent membrane. 



At these parts the minute objects I have described were found 

 clustered on the inner surface of the membrane. In all the hairs in 

 Avhich they were found, and in all the patients, these bodies were the 

 same in size, and refracted light in the same way. They were found 

 frequently in pairs, the long axis of each member of the pair forming 

 a continuous line. Sometimes three of them were found end to end 

 with an appearance of one continuous sheath for the three. These 

 appearances are characteristic of bacteria in development. 



In seven cases in which a treatment was applied that was designed 

 to arrest the development of organisms, and mechanically to prevent 

 their being transported from one hair to the other, the disease at once 

 ceased to spread. In one case, whilst the patches under treatment had 

 been arrested, and new hairs were coming on them, two other patches 

 had appeared unobserved on other parts of the head. 



The same treatment at once arrested the growth of these new 

 patches. 



I have taken much pains to represent the size of these bodies by 

 means of camera drawings, and I believe I have succeeded fairly well ; 

 but I confess to have found it very difficult to get the exact size. As 

 many measurements made of the same objects agreed with each other 

 I believe the drawings may be taken as a guarantee, both of size and 

 shape. 



In order further to ensure accuracy in this respect I obtained the 

 kind assistance of Mr. Noble Smith, whose capacity as an accurate 

 draughtsman in all that relates to microscopic objects is recognised 

 and appreciated. Fig. 2 was prepared from a drawing by Mr. Smith. 

 He determined the outlines of the hair, and drew a number of the 

 objects (or organisms) to the size in which he saw them. The others 

 were filled in to the scale determined by Mr. Smith. The magnifying 

 power represented in the drawing was estimated by measuring the 

 hair. 



Clusters of the organisms were also found in dammar preparations 

 in which the hair was found split into shreds. These shreds were 

 sometimes so thin that the objects which I am describing were seen 

 with much distinctness. 



The order of development of the organisms, or the different stages 

 of their action in breaking up the hair shaft, I believe to be indi- 

 cated by the appearances which I have figured in the drawings. In 



