208 BACTERIOLOGY. 



metal, with asbestos packings. The syringes commonly 

 employed are those shown in Fig. 42. A, Koch's ; B, 

 Strohschein's ; C, Overlack's. 



For the operations requiring exact dosage experi- 

 ence has led me to prefer a syringe after the pattern 

 of 0, in Fig. 42, i. e. y of the design commonly used 

 by physicians. The reason for this is as follows: 

 In making hypodermic injections or injections into the 

 circulation, there is a certain amount of resistance to the 

 passage of fluid from the needle. If one overcome this 

 resistance by means of a cushion of compressed air, as 

 is the case in syringes A and B of Fig. 42, the sudden 

 expansion of the air in the body of the syringe when 

 resistance is overcome, frequently causes a larger amount 

 of fluid to be ejected from the needle than was desired. 

 On the other hand, no such accident is likely to occur 

 when the fluid is forced from the barrel of the syringe 

 by the head of a close-fitting piston, with no air inter- 

 vening between the fluid and the head of the piston. 

 With such an instrument, properly manipulated, the 

 dose can always be controlled with accuracy. 



INOCULATION INTO THE LYMPHATIC CIRCULATION. 

 Fluid cultures or suspensions of bacteria may be in- 

 jected into the lymphatics by way of the testicles. The 

 operation is a simple one. One simply plunges the 

 point of the hypodermic needle directly into the sub- 

 stance of the testicle and then injects the amount 

 desired. 



Injections made in this manner are sometimes fol- 

 lowed by interesting pathological lesions of the lym- 

 phatic apparatus of the abdomen. 



