42 ANATOMY OF THE LYMPHATIC SYSTEM. 



is the best plan : the anterior wall of the chest of a just-killed rabbit 

 or guinea-pig having been removed, the vena cava ascendens is 

 ligatured near its entrance into the auricel, the pleura separated from 

 the diaphragm, and the lungs and heart cut out. In this way the 

 pleural surface of the diaphragm can be exposed without being 

 smeared with blood. After this, each half of the centrum tendineum 

 is pencilled separately two or three times with a fine camel's-hair 

 brush dipped in serum, commencing in the middle line, and carrying 

 the brush outwards ; a quarter or half per cent, solution of nitrate of 

 silver is poured on the pencilled surface, and is allowed to remain 

 there for three to five minutes, after which it is replaced by distilled 

 water : this is changed two or three times. After that the whole 

 diaphragm, together with the ring of cartilage and bone to which it 

 is attached, is cut out, brought into a large capsule with water. As 

 soon as the pleural surface assumes a yellowish-brown colour, the 

 centrum tendineum is divided into a number of pieces, which are 

 floated on object glasses and mounted in glycerine. In a similar way 

 one proceeds if it is intended to demonstrate the lymphatics of the 

 abdominal surface of the centrum tendineum ; the abdominal surface, 

 having been exposed, is pencilled and treated as above. 



The lymphatics of the diaphragm may be also '-injected, either by 

 Recklinghausen's method, that is, by injecting a few c.c. of milk into 

 the abdominal cavity of a living rabbit or guinea-pig, and by killing 

 the animal after 12 to 24 hours (it is desirable to stain afterwards the 

 centrum tendineum with silver) ; or by the method of Ludwig and 

 Schweigger-Seidel, viz. by pouring on the abdominal surface of the 

 diaphragm of a fresh-killed rabbit a few c.c. of a watery solution of 

 Berlin blue, in which a fine precipitate of Berlin blue granules had 

 been effected by the addition of a small quantity of alcohol, and by 

 carrying an artificial respiration on for 1 5 to 30 minutes. A more simple 

 method, which gives better results, is the following : into the ab- 

 dominal cavity of a living middle-sized rabbit or guinea-pig, which had 

 been left without food for 24 hours, 5 to 10 c.c. of a five per cent, solu- 

 tion of Brucke's Berlin blue are injected ; after 4 to 8 hours the animal 

 is killed by bleeding from the crural artery or by strangulation, and is 

 allowed to become perfectly cool. In exposing the pleural surface of 



