10 LABORATORY EQUIPMENT 



syringes, or such as can be sterilized easily, are preferable. Air bubbles 

 are to be carefully guarded against in order to exclude the danger from 

 air embolism. 



If infectious material is used for injection, it is advisable in such 

 instances' to place a small piece of cotton moistened in alcohol or a 5 

 per cent, carbolic acid solution around the point of union between the 

 needle and the barrel of the syringe to prevent the possible escape of any 

 fluid which usually occurs at this point. 



After inoculation is completed, the needle should be quickly with- 

 drawn, a small piece of non-absorbent cotton placed upon the needle 

 puncture and compression applied. If non-virulent bacteria or albumin 

 is injected, the bleeding may be almost instantly controlled by firmly 

 squeezing the vessel above the puncture wound with the edge of one's 

 finger nail. 



In guinea-pigs intravenous inoculation is more difficult, as here there 

 are no large superficial veins. The Jugular or Iliac vein is therefore 

 chosen, and must be dissected free. It is not necessary to tie off the vessel, 

 but the wound should be firmly compressed by means of clean gauze or 

 cotton. Morgenroth has substituted the simpler method of 

 Intracardial intracardial inoculation. The point of maximum pulsation of 

 Injection, the heart to the left of the sternum is made out by palpation 

 and a thin sharp needle is inserted at the specified area. The 

 spurting of blood indicates that the needle is within the heart. Thereupon 

 the already filled syringe is carefully fitted on to the needle and the con- 

 tents slowly injected. The syringe is then detached from the needle and 

 blood is again allowed to spurt out in order to be absolutely convinced 

 that the needle was still in the heart. It is next quickly withdrawn. By 

 this method it is possible to inject about 1 1/2 c.cm. directly into the blood 

 stream. 



In dogs, sheep, goats, horses, etc., the intravenous injection is given into the jugular 

 vein directly through the skin which must be thoroughly shaved, cleaned and dis- 

 .infected. Compression by the finger makes the vein more prominent. 



In dogs the popliteal vein is frequently selected. In man the intravenous injection 

 is given into one of the veins on the anterior surface of the elbow joint. 



Several general rules are to be observed when giving intravenous in- 

 oculations. First of all, only small quantities of fluids should be injected; 

 secondly, the temperature of the fluids for injection should not differ from 

 that of the body; thirdly, substances that are strongly hemolytic may pro- 

 duce marked disturbances or even sudden death of the animal; fourthly, 

 if an animal is to be frequently inoculated it is best to puncture the vein 

 for the first inoculations as far peripherally as possible and give each subse- 

 quent injection more centrally, for very often thrombi are formed at the 

 site of inoculation. 



