1 88 SUPPURA TION AND ALLIED CONDITIONS. 



In a case of erysipelas the streptococci are found in large 

 numbers in the lymphatics of the cutis and underlying tissues, 

 just beyond the swollen margin of the inflammatory area. 

 As the inflammation advances they gradually die out, and 

 after a time their extension at the periphery comes to an 

 end. In the affected area there are the usual changes 

 found in inflammation, great leucocytic emigration and 

 serous exudation with formation of fibrin at places, but 

 there is no suppurative liquefaction of the tissues. The 

 streptococci may extend to serous and synovial cavities and 

 set up inflammatory or suppurative change, peritonitis, 

 meningitis, and synovitis may thus be produced. 



Methods of Examination. These are usually of a com- 

 paratively simple nature, and include (i) microscopic 

 examination, (2) the making of cultures. 



(1) The pus or other fluids should be examined micro- 

 scopically, first of all by means of film preparations in order 

 to determine the characters of the organisms present. The 

 films should be stained (a) by one of the ordinary solutions, 

 such as carbol-thionin blue (p. 109), or a saturated watery 

 solution of methylene-blue ; and (b) by Gram's method. 

 The use of the latter is of course of high importance as an 

 aid in the recognition. 



(2) As most of the pyogenic organisms grow readily on 

 the gelatine media at ordinary temperatures, pure cultures 

 can be readily obtained by the ordinary plate methods. 

 But in many cases the separation can much more rapidly 

 be effected by the method of successive streaks on agar tubes 

 which are then incubated at 37 C. When the presence of 

 pneumococci is suspected this method ought always to be 

 used, and it is also to be preferred in the case of strepto- 

 cocci. Inoculation experiments may be carried out as 

 occasion arises. 



