EXPERIMENTS UPON 



109 



with a pair of sterilised forceps, and with a pair 

 of sharp sterilised scissors, or with a tenotomy 

 knife, a minute incision is made. A sterilised 

 platinum ose is charged with the material to 

 be inoculated, and the loop is gently inserted 

 under the skin, forming a small pocket in the 

 subcutaneous tissue. The needle is then with- 

 drawn, and the sides of the wound gently pressed 

 into apposition. In a mouse the same process 

 is adopted, with the exception that the root of the 

 tail is the usual site of the operation. In a method 

 suggested by Koch an assistant can be dispensed 

 with : a glass bell reversed is placed as a cover 

 to a wide-mouthed glass jar, in which a mouse 

 is held by the tail with a pair of forceps, while 

 the cover is so placed over the mouth of the, 

 jar as to leave a small interval near the rim 

 uncovered. The mouse rests with its head down- 

 wards and with its feet against the inner wall of 

 the jar, and in the interval between the cover 

 and the rim the root of the tail is exposed, 

 and must be cleansed and treated as already 

 described. 



Special Operations. In many cases it is 

 absolutely necessary to perform an operation of 

 greater severity. After the administration of an 

 anaesthetic, infective material may be introduced 

 into the peritoneal cavity by the performance of 

 abdominal section, or injected into the duodenum 

 in the manner employed in the case of Koch's 



