18 EXERCISES IN THE PREPARATION OF TISSUES. 



cannula filled with salt solution is passed in as far as it will go, and 

 is tied in by tightening the loop, secure this by a second knot. Fill the 

 caimula completely with salt solution by means of a fine-pointed pipette 

 to displace air bubbles, and slip the short rubber connection of the 

 glass-pressure apparatus on to the cannula. The latter must also be 

 completely filled with salt solution before connecting. The salt solution 

 is now allowed to flow into the vessel by opening the clip on the 

 pressure tube, and the remaining blood is to be washed out. As 

 soon as the fluid comes only faintly tinged with blood from the 

 sinus stop the injection and substitute saturated corrosive sublimate 

 solution in normal saline. To do this detach the pressure tube 

 from the cannula, empty and, after refilling with corrosive, re-attach 

 to the cannula, being careful not to displace the latter during the 

 operation. The corrosive is now run in. The tissues will turn white 

 when reached by the reagent, and the injection will be complete. 

 If necessary increase the pressure by raising the thistle tube. A 

 column of pressure nearly two feet in height can be brought to bear, 

 but less than this will be required. 



After 20 minutes open the body cavity freely, rinse the surface of 

 the organs with water, and quickly remove the parts required by 

 cutting them out with scissors. (Metal instruments are blackened by 

 corrosive. ) 



Remove the following organs : (a) Liver, Kidneys, Small Intestine, 

 Stomach, Vago-sympathetic Ganglion, Gastrocnemius Muscle, (/>) the 

 upper half of the femur including its head, and (c) both P]yes. 



After Hardening 1 



Put (a) arid (c) into a bottle with 50 C - C - of 70^ c - alcohol tinted with 

 iodine to a sherry colour, the latter loses colour so long as uncombined 

 corrosive is present and must be renewed with each change of spirit until 

 the discoloration ceases. The iodine helps to remove the corrosive, 

 forming iodide of mercury. The alcohol is changed every 12 or 24 

 hours, each 24 hour's change being K)P- C - stronger than the preceding, 

 until full strength methylated spirit is reached. Label the bottle for 

 guidance as follows : 



Always employ tkix system of hiMUn.y when rrr</iuy out (t 

 process. 



