4^86 APPENDIX. 



e. Upon removal of the injecting apparatus the cut end 

 of the blood-vessel or other organ through which it 

 was inserted should be immediately ligatured or 

 clamped, in order to guard against reflux. 



2. Coarse injection, for anatomical purposes. 

 Complete satisfaction may be obtained by using a mix- 

 ture of French blue and water in the proportion of a tea- 

 spoonful to half a tumbler. The mixture should be well 

 stirred immediately before use, and it may be introduced 

 under water or otherwise as occasion demands. Most 

 satisfactory results are to be obtained with this mixture 

 by injecting piecemeal from such of the larger vessels as 

 may be desirable. 



For permanent anatomical preparations plaster of Paris 

 may be preferably employed. Mix with two-thirds its 

 bulk in water and colour with French blue or vermilion ; 

 stir thoroughly and strain through two thicknesses of 

 fine muslin. The mixture thus prepared will remain for 

 8 — io minutes sufficiently fluid for all practical purposes. 



3. Fine injection, for histological purposes. 



Allow a given quantity of gelatine to stand for 3 — 4 hours 

 in twice its bulk of cold water; heat slowly until quite 

 fluid and colour to taste with Berlin blue or carmine. 

 Inject when lukewarm, the animal being immersed in 

 water at the same temperature. 



In the above process the following precautions should 

 be taken. 



a. The point of the cannula should bear a slight con- 

 tusion near its tip, round which the thread may bite 

 when ligatured. 



b. The cannula should be as short as possible, and 

 there should be attached to its base an inch or so of 

 india-rubber tubing to receive the nozzle of the 

 syringe. 



c. The cannula should not be inserted until all bleed- 

 ing has ceased. 



