SYMPTOMS 133 



110. Symptoms. The symptoms vary according to the 

 course of the disease. Two classes are recognized, viz. :( i ) the 

 chronic form, which is most common, and (2) the acute form 

 or miliary tuberculosis. 



The symptoms of chronic tuberculosis depend upon the 

 location of the lesions and their extent. When the lesions are 

 situated deeply and are not of great extent, they may exhibit 

 no visible evidence of their presence. In such cases the in- 

 fected animal may present the picture of perfect health and 

 show no disturbance of function. Indeed, some animals in which 



inoculated by removing the cap. With suflicient opportunity for the in- 

 terchange of air little evaporation takes place, and contamination of the 

 culture is of very rare occurrence. In inoculating these tubes, bits of 

 tissue, which include tuberculous foci, especially the most recent, are 

 torn from the organs and transferred to the serum. Very little crushing, 

 if any, is desirable or necessary. I think many failures are due to the 

 often futile attempts to break up firm tubercules. Nor should the bits of 

 tissue be rubbed into the surface, as is sometimes recommended. After 

 a stay of several weeks in the thermostat, I usually remove the tubes 

 and stir about the bits of tissue. This frequently is the occasion for a 

 prompt appearance of growth within a week, as it seems to put certain 

 still microscopic colonies in or around the tissue into better condition 

 for further development. The thermostat should be fairly constant, as 

 urged by Koch in his classic monograph, but I look upon moisture 

 as more important. If possible, a thermostat should be used which is 

 opened only occasionally Into this a large dish of water is placed, 

 which keeps the space saturated. Ventilation should be restricted to a 

 minimum. As a consequence, moulds grow luxuriantly and even the 

 gummed labels must be replaced by pieces of stiff manila paper fastened 

 to the tube with a rubber band. By keeping the tubes inclined, no 

 undue amount of condensation water can collect in the bottom, and the 

 upper portion of the serum remains moist. The only precaution to be 

 applied to prevent infection with moulds is lo thoroughly flame the 

 joint between tube and cap as well as the plugged end, before opening 

 the tube. When test tubes are employed it is well to dip the lower end 

 of the plug into sterile molten paraffin and to cover the tube with a 

 sterilized paper cap. The white bottle caps of the druggist are very ser- 

 viceable. " 



While the tuberculous material is perfectly fresh (uncontaminated ) 

 and in the early stages of the disease, it is safer to inoculate a guinea 

 pin-, and after the lesions begin to develop to chloroform it and make 

 the cultures from the recently affected liver or spleen. 



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