EXAMINATION OF ANIMALS EXPERIMENTED UPON. I 13 



through the ribs on either side of the sternum with 

 sterilised scissors, and turning* the sternum up 

 where it will be out of the way. The pericardium 

 is then opened, and the right auricle or ventricle 

 pierced with the point of a sterilised scalpel, and 

 inoculations and cover-glass-preparations are made 

 from the blood which escapes. 



The lungs also require to be especially studied. 

 They should be incised with a sterilised scalpel, 

 and inoculations and cover-glass-preparations made 

 from the cut surface. It may be necessary to 

 embed a piece of lung or fragment of spleen, so 

 that it shall be free from air. This may be done 

 by isolating a fragment with the precautions just de- 

 scribed and depositing it upon the surface of a test- 

 tube of nutrient agar-agar. The contents of another 

 tube, which have been liquefied, and allowed to 

 cool almost to the point of gelatinisation, must then 

 be poured over it. From a potato a little cube 

 must be cut, the tissue deposited in the trough 

 thus formed, and the cube replaced. Blood may 

 also be taken directly from a vein by laying it bare 

 by dissection, making a small section with sterilised 

 scissors, and inserting an ose, the needle of a 

 Pravaz' syringe, a capillary tube, or the extremity 

 of the capillary neck of a Sternberg's bulb. If the 

 cultivation is contaminated by the presence of 

 putrefactive or other micro-organisms they must be 

 isolated subsequently by carrying out a series of 

 plate-cultivations. ~ 



