INJECTION OF LYMPHATICS. 181 



to supply the place of the watery fluid which becomes 

 lost by evaporation. 



Although in many cases it is better to use an ap- 

 paratus of the kind above described, which enables 

 the pressure which is being employed to be exactly 

 estimated, yet it may be stated that with a little 

 experience the lymphatic vessels, especially those in 

 the firmer tissues and organs, may often be injected 

 with great success by using simply an ordinary 

 Pravaz subcutaneous syringe provided with a line 

 canula, driving the injecting fluid into the tissue 

 merely by the pressure of the finger. It is true that 

 extravasations are very apt to be produced opposite 

 the point of the canula, but these can often be util- 

 ized in the manner before mentioned by gently 

 pressing on them and endeavoring to induce the in- 

 jection to pass into the lymphatic vessels. 



In rare cases a vein is pierced by the canula, and 

 the system of blood capillaries of the part is then 

 apt to become filled, but both the vessels themselves, 

 and the meshes they form, are much smaller than 

 the lymphatic capillaries, and a knowledge of their 

 general appearance and mode of arrangement in the 

 particular tissue will prevent any error from arising 

 in this way. 



Preparation 8. The lymphatics of the dia- 

 phragm may be injected with Berlin blue during 

 life. A young rabbit is chosen, and enough chloral 

 hydrate is injected under its skin to anaesthetize it 

 completely (about 8 minims of a 50 per cent, solution 

 will suflice). The skin of the belly is then cut 

 through for a couple of inches close to the ensiform 

 cartilage, and the edges are held aside by an assistant, 

 and the muscular wall having been pinched up a. 

 blunt-pointed canula is passed obliquely into the 

 cavity of the peritoneum at its upper part, due care 

 being taken to avoid the liver and stomach. About 

 five cubic centimetres of a saturated solution of 

 Berlin blue, previously warmed, are now injected 

 through the canula, which is then withdrawn and 

 16 



