64 MICRO-ORGANISMS AND DISEASE [cHAP. 



at all, and which can easily be employed in the last case, is 

 this ; deposit from the pointed end of a capillary pipette a 

 droplet of some sterile fluid (broth or thoroughly-boiled 

 saline solution) on the spot of the solid medium on which 

 the organisms are growing, then scratch this spot with the 

 end of the capillary pipette in order to get the organisms off 

 from the solid basis and mixed with the drop of fluid 

 deposited there, then let this drop again ascend into the 

 end of the capillary pipette, and withdraw this altogether. 

 All this can be done without lifting out the cotton-wool 

 plug of the test tube or flask in which the growth is 

 proceeding. 



If one has to use a particle of tissue the surrounding 

 portions of which are probably contaminated by putrefactive 

 organisms — e.g. a tubercle in the lung or a tubercle in the 

 spleen — it is well to follow Koch, and to disinfect the 

 surrounding parts by just washing them with a dilute solution 

 of corrosive sublimate, and then to remove these parts with 

 clean scissors so as to obtain the central particle which one 

 wishes to use for inoculation ; of course one must not steep 

 the organ too long in sublimate solution, since this would 

 naturally destroy all organisms. 



All these methods can be easily modified according to the 

 requirements of the special cases, and it is not necessary 

 here to give more than what has already been described in 

 the preceding.! 



3. Fixing of cultures. — In connection with this a method 

 must be mentioned for the permanent fixing of plate- and 

 tube-cultures. The growth in these can be at any moment 

 arrested, and all further contamination and growth in 



^ Compare also Koch, Untersuchungen iiber pathogem Bacterieii, in 

 Berichle aus dem k. Gesundheitsamte, Berlin, 1881 : and Die Aetiologie 

 d. Tuberculose, Berlin, klin. Wochenschrift, No. 15, 1882. 



