TUBERCULAR EXPECTORATION 361 
that diffuse daylight had a similar effect ; cultures of tubercle bacilli die if they are 
exposed close to the window for five to seven days.' 
Feltz asserted that pulverized tubercular sputum exposed to sunlight was 
virulent after one hundred and forty days. Migneco,' as the result of a number of 
experiments, makes the following conclusions : — 
1. That sunlight has an injurious effect on Bacillus tuberculosis as upon 
other organisms. 
2. That tubercle bacilli contained in sputum on soiled linen and woollen 
stuffs do not withstand the action of sunlight for as long a period as 
twenty-four to thirty hours — if the layer of sputum be not too thick. 
3. The virulence of the tubercle bacilli gradually diminishes after ten to 
fifteen hours of exposure to sunlight, and after this period is lost. 
Ransom and Sheridan 2 shewed that tubercle bacilli in sputum and in culture, 
and also in dry and finely divided material exposed to the action of light and air, 
quickly lose their virulence. 
Sawizky 3 undertook two sets of experiments, in one of which tubercular sputum 
was dried and preserved in a dark place ; in the other the sputum was exposed for 
various periods to the action of sunlight. His results shew : — 
I. That in ordinary living rooms, dried tubercular sputum retains its 
virulence for a period of two and a half months. 
1. The virulence of such a sputum is not suddenly, but is gradually, lost. 
3. Dried tubercular sputum exposed to action of direct sunlight loses its 
virulence similarly to sputum kept in the dark. 
The results of the investigations of these different authors on the action of 
light on tubercle bacilli in sputum thus appear to be somewhat at variance, and the 
action of light on the organisms in sputum expectorated on the sidewalks of public 
thoroughfares under all the varying conditions of wind, sunshine, and rain of an 
English climate, still requires investigation. This will form the subject of a subsequent 
communication. 
The occurrence of tubercular sputa among the many masses which testify to 
' the disgusting and dangerous habit ' of expectorating in the public thoroughfares of 
all large towns is illustrated in the following table. The expectorations were 
collected during the winter months, by means of sterilized swabs and placed in 
sterilized test tubes. Portions of each were inoculated subcutaneously into two 
guinea pigs, which were kept under observation during the subsequent eight weeks 
or more. Other portions were used to make two smears from each on glass slides, 
which after being stained by Ziehl. Niellsen's method were examined under a one- 
twelfth O.I. objective. Mucous, muco-purulent, and purulent accumulations were 
taken indiscriminately, only the most liquid expectorations being neglected. 
I. Migneco, Arch. f. Hygiene, XXV, p. 361. 
2. Ranson and Sheridan, New York Medical Journal, 1894, No. 12. 
3. Sawizky, Inaug. Dissertn., St. Petersburg, 1891 ; Centr. f. Bakt., 1892, p. 153. 
