LABORATORY MAXIMS. 



1. See that the working table, instruments, and all pieces of appar- 

 atus used are thoroughly cleaned at the close of each exercise. 



2. Unless otherwise directed all cultures, other than those in gelatin, 

 are to be grown in the incubator. 



3. Gelatin cultures should not be put in the incubator. 



4. In opening tubes of media or cultures, always flame the open end 

 of the tube immediately after withdrawing the plug. If the tubes 

 have been standing for some time the surface of the plug should be 

 flamed before drawing it out. Never allow the tube end of the plug 

 to touch, while out of the tube, any article by which it could become 

 contaminated. It should be held by the top between the fingers. 



5. In every case where a platinum wire loop or needle is used for 

 making cultures or withdrawing media it should be carefully heated 

 in a gas flame both immediately before and after using. The heated 

 wire must be allowed to cool before making cultures. 



6. If by accident, a drop or more of a culture should be spilled upon 

 the table or floor, pour over it a sufficient quantity of a disinfectant 

 (corrosive sublimate solution i-iooo, or a 5% solution of carbolic acid) 

 to completely cover the affected area. After this has acted for ten 

 minutes wipe it up and boil or burn the cotton or cloth. If any of the 

 culture should drop on the hands or clothing a disinfectant should be 

 applied immediately. 



7. In sterilizing culture media, always see that there is enough water 

 in the pan of the steam sterilizer or in the water bath before lighting 

 the gas. Do not put the media in a sterilizer and leave the laboratory. 



8. Always disinfect, by boiling, all cultures before cleaning the 

 tubes or plates containing them. 



9. At the beginning of each laboratory session read the directions 

 for the next exercise in order to be able to make any preliminary 

 preparations which may be required. 



