10 LABORATORY EQUIPMENT. 



ear. No force should be used with the injections; the fluids should be 

 allowed to flow into the blood stream very slowly. Glass syringes, or such 

 as can be sterilized easily, are preferable. Air bubbles are to be carefully 

 guarded against in order to exclude the danger of air embolism. 



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

 stances, to place a small piece of cotton moistened in alcohol or carbolic 

 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After inoculation is completed, the needle should be quickly withdrawn, 

 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 intra- 



Intracardial car dial inoculation. The point of maximum, pulsation of the 



Injection, 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 contents 



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 



is still in the heart. It is next quickly withdrawn. By this method it is 



possible to inject about 11/2 c.c. 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 disinfected. 

 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 inocu- 

 lations. 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. 



