428 BACTERIA PATHOGENIC TO MAN 



zones of small cells around them they are seen in great numbers, wind- 

 ing about among the cells and forming a sort of network. In the minute 

 foci of small cells one or two fragments of threads are generally seen, 

 and a moderate number in the small abscesses. In the areas of more 

 diffuse infiltration these threads are abundant. No other micro-organ- 

 isms can be found except in the pneumonic area of the left lung, where 

 some groups of cocci are seen. The thread-like organisms are also 

 found in this area and in the other foci scattered through the lung. 



The staining methods described by Flexner were found to give the 

 best results. The most reliable and the one requiring the least time 

 is a modified Gram's method. The sections stained with aniline- 

 gentian violet are dipped for a short time in a diluted Gram's iodine 

 solution and then treated with aniline oil until sufficient color has been 

 removed. The aniline oil is then washed out with xylol, and the section 

 is mounted in xylol balsam. The other method mentioned by Flexner 

 was found to be less reliable, but gave more beautiful results when 

 successful. The specimens are first stained with dilute hsematoxylin 

 solution to bring out the nuclei of the cells and then are stained with 

 carbol-fuchsin and decolorized with aniline oil as before. Long staining 

 with carbol-fuchsin and careful treatment with aniline oil are necessary 

 for success. Many times the micro-organisms were completely decolor- 

 ized by this method, but when successful the dark-red threads winding 

 among the bluish nuclei produced a striking picture. 



Culture Experiments. Six tubes of Loeffler blood serum were inocu- 

 lated from the kidneys. The tubes were placed in the incubator. On 

 the third day after inoculation minute white colonies appeared in 

 some of the tubes, and on the fifth day all the tubes showed from three 

 to ten or twelve similar colonies in each. The colonies increased in 

 size until some of them reached a diameter of one-eighth of an inch, 

 but most of them were smaller. The color, at first white, changed to 

 yellowish-white and then to a decided pale yellow. Having attained 

 a certain size at the base, the colonies ceased to extend, but became 

 more and more prominent. The growth was apparently more rapid 

 at the periphery, and the fully developed colony was round, with convex 

 sides and with a cup-shaped depression at the top. The height of the 

 colony was sometimes greater and sometimes less than the diameter 

 of the base. The well-developed colonies cling firmly to the surface 

 of the medium and are not easily detached or broked up. The growths 

 in all of the tubes were absolutely pure, and consisted of branching 

 threads like those found in the sections. A more minute description 

 of these organisms will be given below. 



Transplants on Loeffler blood serum produce a pale sulphur-yellow 

 growth, forming a layer with a slightly irregular and wrinkled surface 

 and prominent edges where the growth continues longest. The color 

 remains the same until the medium dries, when it becomes white. The 

 growth clings so tenaciously to the surface of the medium that in remov- 

 ing a specimen for examination a portion of the blood serum also is 

 torn away. 



