COLLECTION OF MATERIAL. 



109 



not less than 10 c.c. of blood should be taken.* This is most 

 conveniently accomplished by using a large hypodermatic 

 needle, and aspirating the blood from a vein at the bend of the 

 elbow — under strict antiseptic precautions. A bandage tied 

 tightly around the arm above the elbow facilitates the operation. 

 The blood thus taken may then be used for cultures in various 

 ways. A good method for general purposes is to empty 

 the syringe quickly into a flask holding 100 c.c. or more of bouil- 

 lon or dextrose-bouillon. The mixture of blood and bouillon 

 should be placed in the incubator for one to two days. If the 

 the bacteria develop, they may be secured in pure cultures by 

 plating, and may be studied further, as the occasion requires. 



At autopsies on human subjects the same principles apply 

 as in the case of autopsies upon animals (see pages 104 and 109). 

 Plate-cultures should be made, if 

 possible, directly from the organs. 

 In all cases organs should be seared 

 with a hot spatula over the point 

 where the platinum wire is inserted. Fig. 40.— Sternberg bulb. 

 The method of isolation by streak- 

 ing the platinum wire containing the material under examina- 

 tion lightly, several times, over the surface of an agar plate, 

 will be found convenient. A still more convenient method 

 is to inoculate the water which is collected at the bottom of a 

 stout agar tube and flood it over the surface of the agar. In 

 the tubes inoculated in this isolated colonies grow out on the 

 surface of the slanted agar. At the same time smears should 

 be made from the organs upon cover-glasses for microscopic 

 study, and portions of the organs should be saved and 

 hardened in alcohol or formalin. 



A convenient device for the collection of infected material is 

 a stiff wire wound with a pledget of absorbent cotton at one end, 



*For examination of blood for typhoid bacilli see Libman. Bui. Johns 

 Hopkins Hasp. Vol. XVII., July, 1906. 



