I I 3 SEPARA TION OF MICRO-ORGANISMS FROM TISSUES. 



The same method may be used in the case of animals, but it is 

 usually better to kill them, and obtain the seed material as described 

 under "dead tissues." 



(c.) Discharges. — This comprehends contents of abscesses, and the 

 excretions from glands {e.g., kidney) in which living organisms 

 capable of cultivation may be present. An abscess should be opened 

 with antiseptic precautions (spray, skin purified, &c), and a drop of 

 pus as it emerges collected on the end of a looped platinum wire, and 

 at once plunged into some sterile nutrient medium. Urine should 

 be collected with similar precautions in a sterile flask, and after cool- 

 ing, some of the deposit drawn into a newly made glass pipette, and 

 transferred to some nutrient medium. Usually the organisms thrown 

 off in the urine are dead. They can be recognised microscopically, 

 but rarely cultivated. An ingenious method of separating the Bacil- 

 lus lepra from the living tissues has already been described (see foot- 

 note, p. 38). 



2. — From Dead Tissues. 



68. Unless taken immediately after death, dead tissues are in general 

 useless for employment as seed material. If they can be secured at 

 once, however, pure cultivations of the micro-organisms which they 

 contain may be obtained with ease. In the case both of man and 

 animals a certain amount of dissection must be carried out with 

 aseptic precautions to obtain this result. In making this dissection 

 only sterile instruments must be employed. All the instruments 

 necessary (several knives, scissors, forceps, Pravaz' syringes, &c.) are 

 thoroughly cleansed, and wrapped in sheets of cotton wool. They 

 are then placed in the hot air steriliser for an hour at 170° C., 1 

 not heated in the flame, as has been suggested, and which is a most 

 extravagant method, as it destroys the temper of steel completely. 

 They are wrapped in cotton wool, to prevent access of atmospheric 

 germs to the sterile instruments, when the outside air regurgitates 

 into the hot air chamber on its beginning to cool. They are only 

 unwrapped from their cotton wool protection immediately before use. 



1 The knives must have bone handles, as, if made of wood, they become in- 

 cinerated. 



