430 BACTERIA PATHOGENIC TO MAN 



These cocci represent the spore form of the organism, and when planted 

 upon blood serum the branching threads again appear. The spores 

 stain readily with carbol-fuchsin and are not easily decolorized. They 

 are spherical, or nearly so, but often appear somewhat elongated, 

 apparently from beginning germination. They are killed by exposure 

 to moist heat of 65 to 70 C. for an hour, but are more resistant to dry 

 heat. Exposure upon a silk thread, to a temperature above 120 C. 

 for an hour and a half did not affect their vitality. The last sixty minutes 

 of this time was at 125 to 127 C., and the bulb of the thermometer 

 was within the tube in contact with the thread. No growth was obtained 

 after an hour's exposure at 135 C. Drying destroys the threads after 

 a comparatively short time, but the spores retain their vitality for an 

 indefinite period. A dried-up potato culture which was planted March 

 1, 1900, and has stood in the laboratory ever since, still retains its 

 vitality at the end of almost four years. Plants made from this specimen 

 upon blood serum show an abundant yellowish growth at the end of 

 twenty-four hours. 



The germination of the spores and the growth of the threads were 

 observed under the microscope in a hanging drop in the chamber of a 

 hollow slide. Here all stages of growth may be seen, from the elongated 

 spore to the fully developed branching organism. The spore sends out 

 a delicate sprout which very early looks like a bacillus with a bulbous 

 extremity. The sprout soon branches, and the growth proceeds rapidly 

 with frequent branching in all directions. Slight clubbing of the ends 

 of the branches is often seen, but generally the ends are not club-shaped. 

 In a few stained specimens an extremely delicate, almost colorless, 

 club-shaped structure was seen at the ends of the branches. This 

 appearance was not constant, and possibly was produced artificially. 

 It can be seen in some of the photographs. 



The development of the spores was not so easily demonstrated. In 

 specimens taken at frequent intervals from potato cultures the threads 

 become more and more broken up into short fragments, and the number 

 of free spores increases very rapidly. Some of the fragments appear to 

 have a spore at each end, and some have three or more spores. The 

 free spores show no regular arrangement, but occasionally a short chain 

 of five or six can be found. 



The identity of this micro-organism is not fully established. It is 

 undoubtedly a streptothrix, but it does not agree in all particulars 

 with any of the varieties described. It approaches most nearly Eppin- 

 ger's variety, but at no stage of its growth is it ever motile. The color 

 and character of the growth upon different media and the sporulations 

 upon potato agree with the descriptions of the streptothrix Eppingeri. 



Animal Inoculations. A number of rabbits and guinea-pigs were 

 inoculated subcutaneously upon the abdomen and in the neighborhood 

 of the cervical, axillary, and inguinal lymph nodes with colonies broken 

 up in salt solution. Indurated swellings were produced at the point 

 of inoculation and a number of abscesses resulted. The abscesses 

 developed rapidly and some of them opened spontaneously, while 



