16 



erine agar slants from the contents of a pustule, and a bouillon 

 emulsion of some of the contents of another was injected into the 

 abdominal cavity of a male guinea pig. The cultures were kept 

 at 35-37, and in twenty-four hours numerous discrete, barely 

 visible, transparent colonies appeared. These were plainly visible 

 in forty-eight hours, and a pure culture from one of them gave 

 the biochemical characters which are described at the end of this 

 bulletin as peculiar to Bacterium mallei. 



The guinea pig showed distinct hyperemia and swelling of the 

 testicles in forty-eight hours. It was chloroformed on the sixth 

 day after inoculation. At autopsy a pin-head-sized, yellowish 

 nodule was found at the point where the needle passed through 

 the muscular wall of the abdomen. The testicles had reached 

 the size of a large walnut and were fused together, and their 

 greatly thickened tunica showed a number of yellowish, caseous 

 foci. There was congestion of the inguinal glands, spleen, liver, 

 and kidneys. No nodules were found in the organs of the peri- 

 toneal and thoracic cavities. Bacterium mallei was obtained in 

 cultures from the testicles. 



Histologic examination (skin pustule, Borrell's stain, kindness 

 of Dr. Brinckerhoff). A section through one of the larger pustules 

 (about 4 millimeters in diameter) (see PL Y) shows a densely 

 infiltrated area in the skin and subcutaneous tissues. This inflam- 

 matory exudate lies chiefly between the muscular layer and the 

 Malpighian cells of the epidermis. The epidermis is raised to a 

 considerable distance above its level in the adjacent normal skin. 

 At the point where it leaves its normal level the deeply pigmented 

 cells of the rete malpighii are seen to be greatly elongated, and 

 just before it reaches its greatest elevation there is a splitting 

 away of the horny layer, which, continuing to a similar point on 

 the opposite side, leaves a space which constitutes the vesicular 

 portion of the pustule. 



Under a high-power lens the contents of the vesicle is seen to 

 be composed of degenerated polynuclear leucocytes and cells from 

 the stratum granulosum, nuclear fragments, and a granular de- 

 tritus which represents the products of cell degeneration and 

 coagulated serum. Beneath this area the cells of the rete show 

 marked infiltration and vacuolation, many of their nuclei staining 

 but faintly or not at all. The deeper-infiltrated area is composed 

 of a dense collection of more or less degenerated leucocytes and 



