54 Dr. A. Ransome and Mr. S. Delepine. On the [May 24, 



tuberculous sputum to dry (a) in air and light, (6) in air and dark- 

 ness, (c) in a close cupboard. 



Fresh sputum, rich in bacilli, was obtained and exposed in watch 

 glasses. Specimen (a) was dry in four days ; specimen (6) in eight 

 days ; and specimen (c) in 19 days. 



Specimens (a) and (6) were closed up as soon as they were dry 

 and kept until specimen (c) was ready, and then portions of the 

 sputum were scraped off the glasses and inoculated into guinea-pigs 

 directly after scraping. Table III gives the results. 



Table III. 



No. 



117. 1.1 (Sputum (a) inoculated subcutaneously into two guinea-pigs, 



118. 2.) (.killed 64 days afterwards, gave well-marked tuberculosis. 



119. 3.") f Sputum (b), similarly used, showed no results 



120. 4.J 153 days after. 



126. 5. Sputum (c) gave well-marked tuberculosis 50 days afterwards. 



The results of these experiments are somewhat anomalous. The 

 sputum was in rather thick masses and thus dried slowly, and would 

 with difficulty be affected by the natural agents to which they were 

 exposed. This fact would probably account for the continued viru- 

 lence of sputa of 1 and 2, but the immunity from sputa 3 and 4, after 

 eight days exposure to a current of air in darkness, is hardly likely 

 TO be due to this exposure ; we can, therefore, draw no decided con- 

 clusion from this series of experiments. 



In the fourth series of observations, the sputum was spread upon 

 paper, and was thus more rapidly dried at the ordinary tempera- 

 tures, about 24 hours sufficing. It was then in most cases scraped 

 and thus partly converted into " tuberculous dust " before being 

 exposed to the same conditions as before. In this way it might be 

 expected to be more readily affected by the elements. 



An attempt was made to measure the amount of air as well as 

 light, an anemometer and a sunshine-recorder being placed near 

 the sputum exposed at the open window. 



Only a rough guess could thus be made as to the quantity of air 

 passing over the sputum, however, for the papers had to be loosely 

 covered with thin gauze to prevent the " dust " from being carried 

 away by the wind, and the anemometer recorded currents in both 

 directions. 



Three sets of experiments were made. 



1. Papers were placed, to be used for control experiments, in the 

 dark, close cupboard. 



2. Papers were placed in the air-shaft of a draught- closet in dim 

 light, pure air only passing through it. 



