272 BACTERIOLOGY. 



closed space, where the opportunities for evaporation 

 are slight. They should always be kept inclined. 



<( The ordinary cotton-plugged test-tubes I do not 

 use, because of the rapid drying out permitted by 

 them as well as the opportunities for infection with 

 fungi. Instead, a tube is used which has a ground- 

 glass cap fitted over it. This cap contracts into a 

 narrow tube plugged with glass-wool; this plug is not 

 disturbed. The tube is cleaned, filled, and inoculated 

 by removing the cap. With sufficient opportunity for 

 the interchange of air very little evaporation takes place, 

 and contamination of the culture is a very rare occur- 

 rence. 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 tubercles. Nor should the 

 bits of tissue be rubbed into the surface, as is some- 

 times 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 occa- 

 sion for a prompt appearance of growth within a week, 

 as it seems to put certain still microscopical colonies in 

 or around the tissues 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 of more importance. If possible a 

 thermostat should be used which is opened only occa- 

 sionally. 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 



