INFECTIVE DISEASES. 



on the solution for ten minutes to h;ilf an hour, then tiULsfer them 

 to ioaine-potassic-iodide solution, until they assume the colour of a 

 tea leaf; then immerse them in alcohol until they are decolorised ; 

 dip them in an alcoholic solution of eosin for a few moments, and 

 then transfer them to clove oil to clarify the film ; to remove the 

 clove oil gently press the cover between tw,j layers of clean filter 

 paper, then mount in xylol Ijalsain. 



A good method for cultivating streptococci is to employ a steril- 

 ised looped platinum wive, and to spread a droplet, for example, of 

 pus or blood, over the surface of nutrient agar-agar solidified obliquely. 



h. c. 'I. 



Fig. 90. — STKErTOcoccus Pyogenks Bovis. Pure-cultures on nutrient 



gelatine. 

 a, Sub-cnlture from agar. h. Sub-culture from broth. 



c, Sub-culture from milk. d. Sub-culture from milk. 



The tubes ai'e then placed in the incubator at 37° C. ; the .strepto- 

 cocci will appear in the course of two or three days in the form 

 of minute dotted colonies. If present alone, and in consiilerable 

 (juantities, the inoculated surface will exhibit a pure cultivation 

 consLsting of a number of such colonies, whilst a flocculent mass is 

 observed in the liquid which collects at the bottom, of agar-agar 

 tubes ; this florculeut mass will be found to be composed of chains. 

 From such a tube inoculate a number of the small flasks employed 

 in Pasteur's laboi'atory for cultivations in hqiiids. In this way 

 a number of pure- cultivations in milk and broth are estaljlished, 

 which can le re.idily examined fi'om time to time. From a pure- 



