1907.] on Certain Seasonal Diseases of the Sheep. 541 



It will thus be seen that, on an average, the rod comes up to 

 something' like half the long measurement of a human coloured blood- 

 corpuscle, sometimes longer, at other times shorter. As found in the 

 natural liquids of the body, it exhibits an extraordinary aptitude for 

 sporing. The spore is smaller than that of any of the other an- 

 aerobic organisms leading a parasitical existence upon the sheep, and 

 can often be distinguished from them by this feature. It is brown- 

 coloured, highly refractile, and located towards the end of the rod, 

 giving to the latter a somewhat lanceolate contour. 



The rod is usually quite immobile, both when in the natural 

 serous effusions of the body and in culture on artificial media. It 

 may happen, however, that, under certain circumstances, it develops 

 some amount of motihty. The ends are rounded, but when the 

 organism is stained, as with Loeffler's blue, certain chromatic points 

 make their appearance, and if one of these does not happen to be at 

 the extreme end, the unstained capsule gives the rod a somewhat 

 tapering appearance. Owing to the presence of these chromatic 

 granules the bacillus may present an irregular or half -digested appear- 

 ance, even in an unstained preparation. 



It may chance that nearly every rod is sporing, and not only may 

 the spore be located towards one extremity, but exquisite drum-stick 

 forms are met with, the delicacy of the rod under such circumstances 

 in contrast with the well defined spore being a notable characteristic. 

 When the spore is just beginning to show, it can be recognised as a 

 little clear point ; this enlarges, becomes more highly refractile, and 

 eventually may protrude at one of the poles. It must l)e remarked, 

 however, that such a drum-stick configuration is by no means dia- 

 gnostic of Braxy ; it is a morphological feature common to almost all 

 the members of the group. 



Two bacilli may often be encountered still united, either at an 

 angle or in a straight line, but it is seldom that the rods are strung 

 in chains, and chains with a zig-zag conformation are almost pro- 

 hibitive of the organism being that of Braxy. Two or more bacilli 

 may lie side by side and closely adherent, possibly overlapping, in 

 which case they may resemble a l)acillus of unusually great length. 



The organism when grown on glucose-beef-tea has a great ten- 

 dency to run into dense masses, in fact to clump, so that when it 

 settles down on the sides of the culture tube the deposit has a dis- 

 tinctly granular appearance. On spreading out a drop of the culture 

 deposit on a slide the same fine particles are visible with the naked 

 eye, or with a pocket lens. On microscopic examination, they are 

 seen to be not merely loosely held together colonies, but to constitute 

 a dense feltwork not easily dissociated. 



Both kinds of blood-corpuscle are invariably absent from the 

 peritoneal liquid even when much blood-stained, and when the liquid 

 is allowed to remain quiescent for a few days, the particulate matter 

 settles down and leaves the liquid above clear but deeply laked. 



