124 BACTERIOLOGICAL ANALYSIS LESSON 



E. PSOROSPERMS IN RABBIT'S LlVER. 



(a) Examination in the v/nstained condition. 



(1) Make a few cuts into the liver and look for white, 

 puriform or caseous masses. 



(2) Remove some of the white substance on to a 

 slide, and tease it out carefully. 



(3) Add a drop or two of a 10 per cent caustic potash 

 or a little iodine solution, and allow either to act for a few 

 minutes. 



(4) Remove the excess of caustic potash or iodine, and 

 then mount the specimen in Farrant's solution. 



Examine with low and high powers, using a narrow 

 diaphragm at the same time. 



(b) Staining of psorosperms. 



(1) Squeeze some of the white matter between two 

 cover-glasses, and when dry pass the films through the 

 flame. 



(2) Stain them in Lofner's methylene-blue, or as for 

 tubercle bacilli, in carbol-fuchsine and methylene-blue. 



In the latter case the psorosperms will appear red. 



Examination of Ice Cream 



(a) Quantitative examination. 



(1) Melt some ice cream (100 cc.) in a sterile beaker at 

 38 C. and add 500 cc. of sterile distilled water to it. 



(2) Prepare plates from the mixture, using ordinary 

 gelatine and also carbolic acid gelatine, inoculating the tubes 

 with quantities varying from '005 to '05 cc. (vide p. 93). 



