BUREAU OF ANIMAL INDUSTRY. 671 



tracliea. Its center was already softened. The organs were appar- 

 ently normal with the exception of the liver, which is extremely pale 

 and bloodless, showing signs of cirrhosis. 



GENERAL CHARACTERS OF THE MICROBE CAUSING PNEUMONIA IN 



SWINE. 



In cover-glass preparations from the organs of animals which have 

 died from inoculation, and of which the rabbit presents the best advan- 

 tages for* study, the microbes appear as oval bodies, measuring about 

 1 to 1.2 micromillimeters in length and .6 to .8 micromillimoter in 

 breadth. When stained by some aniline, such as an aqueous solution 

 of methyl violet or an alkaline solution of methylene blue, their ap- 

 pearance is very much like that of the microbes of rabbit septicaemia. 

 The two extremities of the longer axis are deeply stained. Between 

 these colored masses a transverse band remains transparent, without 

 any color. This unstained portion may vary between one-fourth and 

 one-half of the entire optical area of the oval. It is limited on either 

 side by a very delicate, stained line (Plate III. Fig. 2; Plate IX, Fig. 1). 

 It is probable that this appearance arises during the elongation of the 

 coccus preparatory to a transverse division into, two, and that the 

 width or this unstained area depends upon the stage of the process. 

 Among the cocci there may be seen in cover-glass preparations of 

 liquid cultures rodlike forms as broad as the cocci, imperfectly seg- 

 mented, and attaining in a few cases a length of 15 to 20 micromilli- 

 meters. These filaments must be regarded as involution forms of the 

 cocci, due to a want of power of division; for such a form is frequently 

 of varying width and the extremities irregularly tapering; moreover, 

 the cultures containing them are invariably found pure when tested 

 on gelatine plates. This abnormal growth is not confined to cultures. 

 It is found in cover-glass preparations made directly from the tissues 

 of animals which have succumbed to inoculation with pure cultures. 

 They are common in mice and rabbits. In the former animals they 

 assume a bacillar form occasionally, in rabbits a form staining very 

 irregularly ancl resembling swollen diplococci. In the earlier exper- 

 iments with this microbe these abnormal appearances were very puz- 

 zling. Inoculation of liquids with these bacteria gave invariably the 

 same form. Gelatine tube cultures and the colonies on plates always 

 proved the same. It became necessary to conclude from these results 

 that, although fatal to these animals to a very high degree, this par- 

 ticular coccus does not find the best conditions for multiplication in 

 these animals ; or else it may be found that some slight variations 

 in the manipulation of cover-glass preparations, a too rapid drying 

 or a greater heat applied to the dried film, may cause changes in the 

 microscopical appearances of the stained germ. Whatever the reason 

 may be, the striking fact remains that in some rabbits the bacteria on 

 cover-glass preparations are regular and uniformly stained at both 

 extremities; in others they are irregular in outline and the staining 

 is not characteristic. 



If a neutralized beef infusion with 1 per cent, peptone be inocu- 

 lated with this microbe a faint opalescence pervades the entire fluid 

 on the following day. There is no membrane present at this stage, 

 nor after several weeks. A pure liquid culture of this microbe is 

 easily distinguishal)le from that of the hog-cholera bacterium. The 

 latter is more opaque, and when the tube is shaken rolling clouds 

 are formed. This is not seen in the faint opalescent liquid of the 



