1906.] Obstruction of the Vence Cavce and the Portal Vein. 281 



end of the injections, and this fluid was produced with a normal capillary 

 pressure. 



If such a procedure be Carried out in the case of a normal animal, no ascites^ 

 is found after intravenous injection of 130 c.c. fluid. 



7. Conclusions. 



Of whatever nature the impediment be which opposes the free flow of 

 blood into the heart and diminishes thereby the diastolic blood quantum,, 

 it will bring about precisely the same effects upon the circulation of the 

 blood. There will be a general rise of systemic pressure affecting all the 

 veins of the body and extending back as far as the capillaries, and a fall 

 of the mean arterial blood-pressure. This effect is due to accumulation 

 of blood in the veins. The venous pressure, however, soon falls to its 

 normal level again, if the animal lives; and the arterial pressure is raised 

 more or less completely to its former level owing to vaso-motor constriction. 

 Dropsy is produced after several hours, whilst the capillary pressure is 

 normal or even below normal. 



The reason why the venous pressure returns to the normal level is because 

 the veins passively distend and likewise the capillaries, which normally are 

 not completely filled. The veins which distend are those of the thorax 

 and abdomen, because the superior and inferior cavae can be seen distended 

 and the liver enlarged; the venae < cavae are less supported than those in 

 other parts of the body, they are situated within the suction action of the 

 thorax, the bed of the blood stream is here smaller than in the more 

 peripheral parts of the body, and muscular tension empties the veins in 

 the latter situation towards the heart. In the erect posture, when gravity 

 is of the greatest importance, the blood will tend to collect in the most 

 dependent parts. 



The dropsy is produced in this situation where the veins and capillaries 

 are distended and where the blood flows with a diminished velocity, and it 

 probably depends entirely upon an altered condition of the vessel wall, and not 

 upon an altered condition of the nutrition of the tissues themselves, as 

 maintained by Lazarus-Barlow (6), although, of course, these experiments do- 

 not disprove Barlow's theory. 



This alteration is probably of a pathological nature and not such as would 

 lead to an increase of the normal function of the capillary endothelium (7).. 

 Raised capillary pressure plays no part in the production of this cedema, and 

 the arterial pressure may be normal or less than normal, it matters not which.. 



It might be argued that during the first hour the raised pressure which 

 occurs would damage the vessel wall, but in those animals which recover 



