330 BULLETIN No. 161 [November, 



Series 2 



PREPARATION A second series of experiments exposing cow ma- 

 AND EXPOSURE nure artificially infected with a pure culture of 



OF SAMPLES , / . .... ^1 



bovine tubercle bacilli was made. The prepara- 

 tion and exposure of these samples were made in the same man- 

 ner as in Series I (see pages 319 and 320). The places of exposure 

 were within a few feet from the places where the samples were ex- 

 posed in the first series. 



WEATHER Table 17 gives the weather conditions during the 



CONDITIONS time of exposure of this series. The same plan 

 is followed as in Table 12 giving the weather 

 conditions in the first series. These conditions were just the re- 

 verse of those in the first series, the first series beginning in the 

 hot month of August, the second in the cooler and more moist 

 month of March. No especially unusual weather conditions oc- 

 curred during this period. 



Manure Exposed in the Sunshine. The results of 

 RESULTS exposing this infected manure in the sunshine are 



given in Table 18. The tubercle bacilli were still 

 alive at the third test after 45 days of exposure. Tho the tuber- 

 culosis produced in each of the two guinea pigs from this test was 

 only slight, as shown when these guinea pigs were killed and ex- 

 amined 53 days later, Guinea Pig 973, inoculated with the dis- 

 eased tissues from these two, produced severe generalized tuber- 

 culosis. Typical cultures were obtained from the diseased tissues 

 of both the original and the secondary inoculated guinea pigs. 

 The samples taken after this date produced no tuberculosis in the 

 six guinea pigs inoculated. 



Manure Exposed in the Shade. The results of exposing the 

 sample in the shade are given in Table 19. Here we find that the 

 tubercle bacilli were alive for 73 days, while in the sample ex- 

 posed in the sun they were dead at this testing. Also the test 

 made on the 45th day shows more severe tuberculosis in the guinea 

 pigs inoculated .from the sample kept in the shade than from the 

 sample in the sun. 



I. As shown by the results in both series of ex- 

 CONCLUSIONS periments, a pure culture of bovine tubercle bacilli 



mixed with cow manure and exposed in the sun- 

 shine in a pasture, remains alive and virulent for approximately 

 two months. 



2. The virulence of the tubercle bacilli in cow manure was re- 

 tained in the samples protected from the sunshine longer than in 

 those exposed in the sun, as shown both by the increased length 



