1906.] Liver Cells to the Blood-vessels and Lymphatics. 



461 



injection, and believes that he can show that the injection material in these 

 preparations has passed from the blood-vessels into the liver cells by way of 

 the lymphatics. 



Schafer(56), in replying to Holmgren's criticisms, points out that although 

 the pressures employed in injecting the preparations described are not 

 known, the appearances cannot be artefacts, for the injection is uniformly 

 present in the cells throughout the liver, except in the immediate neighbour- 

 hood of extravasation, where it is absent or imperfect. The appearances 

 which Holmgren considered to indicate the injection of perivascular lymph 

 spaces are merely clefts in the gelatine produced by shrinkage during 

 the process of hardening by alcohol, a portion of the gelatine tending, 

 under these circumstances, to adhere to the wall of the capillary. It is this 

 layer which Holmgren has taken to represent the injection of a perivascular 

 lymphatic. 



Description of our Experiments : Results Obtained. 



It was to settle the question as to what amount of pressure is required 

 to inject the liver cells from the blood-vessels that we began our work, a 

 preliminary note of which was published last year. We made a com- 

 mencement by injecting rats with carmine gelatine from the aorta in the 

 manner already described. The rat was selected partly because of its small 

 size, and partly because Dr. H. K. Anderson, of Cambridge, had sent to 

 Professor Schafer last summer specimens of rat's liver in which the cells were 

 beautifully injected with carmine gelatine.* 



In all, 20 rats were injected from the aorta close to the heart, at pressures 

 varying from 80 to 120 mm. Hg. The inferior vena cava was opened 

 above the diaphragm, and in most cases remained open so as to allow a free 

 escape of blood and injection mass. In others the inferior vena cava was 

 ligatured after the injection mass had begun to flow out, and the injection 

 pressure was maintained some minutes longer before tying the portal vein. 

 In all these rats the liver cells contain carmine gelatine. Some of the best 

 specimens were obtained with a pressure of 80 mm. Hg in the aorta, and 

 a free escape from the inferior vena cava during the whole period of injection, 

 which occupied about five minutes. This pressure cannot be called 

 excessive. The flow from the inferior vena cava was quite free all the time, 

 and the pressure in the vessels of the liver must have been very low. Fig. 4 

 is from a specimen injected at this low pressure. Increase of pressure 



* Dr. Anderson informs us that the rat was injected from the aorta, and that 

 during the injection there was a free escape from cut intercostal arteries ; therefore the 

 pressure in the portal vein could not have been excessive. 



