ANTI- VENOMOUS SERUM AND ITS PREPARATION. 419 



Fig. 159. — When a charge of anti-venomous serum is taken up into the barrel of a 

 syringe previous to injecting the content under the skin or direct into a vein, air 

 is often drawn up also. To expel the air, hold the syringe with the point upwards 

 and gently press the piston till the serum begins to ooze from the point of the 

 needle 



