228 Experimentation upon Animals 



is diflScult. One method that has been recommended is to tie the 

 animal to a tray or board, on its back, anesthetize it, and, just before 

 it dies, quickly open the thoracic cavity, and cut through the heart 

 with scissors. The animal at once dies, the blood pouring out into 

 the pleural cavities. After coagulation the serum can be secured 

 by carefully pipetting it from the cavities. 



Post-mortems. — Observation of experiment animals by no means 

 ceases with their death. Indeed, he cannot be a bacteriologist who 

 is not already a good pathologist and expert in the recognition of 

 diseased organs. 



When an autopsy is to be made upon a small animal, it is best 

 to wash it for a few moments in a disinfecting solution, to kill the 

 germs present upon the hair and skin, as well as to moisten the hair, 

 which can then be much more easily kept out of the incision. 



Small animals can be tacked to a board or tied, by cords fastened 

 to the legs, to hooks soldered to the corners of an easily disinfected 

 tray. The dissection should be made with sterile instruments. 

 When a culture is to be made from the interior of an organ, its surface 

 should first be seared with a hot iron, a puncture made into it with a 

 sterile knife, and the culture made by introducing a platinum wire. 



If the bacteriologic examination cannot be made at once, the or- 

 gans to be studied should be removed with aseptic precautions, 

 wrapped in a sterile towel or a towel wet with a disinfecting solution, 

 and carried to the laboratory, where the surface is seared and the 

 necessary incisions made with sterile instruments. 



Fragments intended for subsequent microscopic examination 

 should be cut into small cubes (of i cc.) and fixed in Zenker's fluid 

 or absolute alcohol. 



Collodion capsules are quite frequently employed for the purpose 

 of cultivating bacteria in a confined position in the body of an animal, 

 where they can freely receive and utilize the body-juices without 

 being subjected to the action of the phagocytes. In such capsules 

 the bacteria usually grow plentifully, and not rarely their virulence 

 is increased. 



The capsules can be made of any size, though they are probably 

 most easily handled when of about 5-10 cc. capacity. The size is 

 always an objection, because of the disturbance occasioned when 

 they are introduced into the abdominal cavity. 



The capsules are made by carefully coating the outside of the 

 lower part of a test-tube with collodion until a sufficiently thick, 

 homogeneous layer is formed. During the coating process the tube 

 must be twirled alternately within and without the collodion, so 

 that it is equally distributed upon its surface. When the desired 

 thickness is attained, and the collodion is sufficiently firm, the tube 

 is plunged under water and the hardening process checked. 



A cut is next made around the upper edge of the collodion film, 

 and it is removed by carefully turning it inside out. In this manner 



