CHAPTER IX 



SCHEME FOR ROUTINE STUDY OF THE VARIOUS 

 GROUPS OF ORGANISMS 



This scheme is to be followed strictly in the study of 

 all organisms, except when special instructions are given, 

 and the student should thoroughly familiarize himself 

 with the different steps. The work of cultivation as 

 described in steps 1,3, and 5 may be divided between two 

 students working together, but all other procedures are 

 to be followed by each individual. 



1. The inoculation of one slant-agar-tube from each 

 individual stock-culture supplied. These inoculated agar- 

 tubes are to be incubated at 37 for 24 hours, unless 

 otherwise instructed. 



2. At the end of 24 hours make from each agar-tube: 



a) A physical description of the culture (see Chap. 

 X). 



b) A hanging-drop examination. 



c) A Gram stained preparation. 



d) An ordinary stained preparation. 



Method of making preparations according to Gram 



a) Prepare a film of the organism to be examined, 

 the same as in the ordinary stained preparation. 



b) Cover with gentian-violet for i minute. 



c) Wash in water, and remove the water by means 

 of filter-paper, leaving the surface moist. 



d) Cover with Gram's iodin solution for 2 minutes. 



e) Pour Gram's iodin solution off and, without 

 washing, place in a watch-glass, film side up, and cover 

 with 96 per cent, alcohol. 



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