58 CLINICAL BACTERIOLOGY AND H^EMATOLOGY 



of sputum made in the manner described. If you find many 

 pneumococci in a case of lobular pneumonia the disease is 

 probably pneumococcic, but it may have been caused by 

 another germ, and the cocci in question may have been nothing 

 more than a secondary infection. A specimen should be 

 stained deeply by carbol fuchsin or methylene blue and 

 searched for bacilli resembling those of influenza, etc., and 

 another should be stained for the tubercle bacillus if the clinical 

 aspect of the case suggests the possibility of a tuberculous 

 origin for the disease. 



Pus is examined in the same way, and presents similar ap- 

 pearances. Most of the cocci are extracellular, but some are 

 frequently contained in the cells, and may then not retain 

 Gram's stain. 



It is not usually necessary to make cultures, as the pneu- 

 mococcus is readily recognized in pathological material from 

 its morphological appearance and staining reactions alone. 

 Where cultures are required, agar is a good medium, but it is 

 improved by the addition of serum, and it must be incubated 

 at the body temperature (growth is much better if the surface 

 of the medium is smeared with a little blood, as in the manner 

 described for cultures of the gonococcus). It is advisable to 

 plate out several tubes in the manner already described (p. 17), 

 and it will usually be found that one or other tube will provide 

 isolated colonies from which pure cultures can be obtained. 

 The colonies are visible after twenty-four hours as very small 

 transparent circular masses, which are but slightly raised and 

 show but little tendency to increase in size on further incuba- 

 tion. They have often a shallow centre and a raised edge, like 

 a red corpuscle. It is a very delicate organism, and one which 

 readily dies out on ordinary media, so that if a culture is to 

 be "kept going" it must be transplanted every two or three 

 days to a fresh tube. This is one of its most characteristic 

 features. 



Vaccine Treatment. Pneumococcic infections are usually 

 very amenable to vaccine treatment. In acute lobar pneu- 

 monia good results have been obtained by a small dose at the 

 outset of the disease ; 5 to 25 millions, the latter being a high 

 dose, only to be used for strong persons in whom the disease 

 is seen early. In this disease time is of great importance, and 

 it is not, as a rule, advisable to wait whilst the patient's own 



