44 ON DIGITALIS, WITH SOME 0T3SERVATI0NS ON THE URINE. 



this extract has been applied to the ceUular tissue, or introduced 

 into the stomach." This conchision appears to be rather more 

 general than facte, at least those which he details, warrant, as 

 in five cases he found the blood coagulated in both ventricles 

 only in one case, in the right ventricle completely in one, and 

 partially in another, while it was fluid in the left ventricle in 

 both these cases, and in both ventricles in two others. In four 

 cases in which dogs were poisoned with digitaline, I found the 

 blood coagulated in the right ventricle, the other being empty in 

 one case, partly fluid and as if curdled in both ventricles in 

 another case, and quite fluid in two others. 



What is wanted in this subject, however, is not so much loose 

 observations of this sort, but definite experiments on the changes 

 of the chemical relations of the blood in regard to the inter- 

 change of gases, such as Bernard made in reference to woorari, 

 and Harley has lately been doing with several of the organic 

 alkaloids. 



On the Cirailation. — Before considering the effect of digitalis 

 on the circulation, it may be advisable to glance at the cause of 

 the pulse, and the arterial tension and the modifications they 

 undergo.* The pnlse is the feeling of a sudden rise experienced 

 by the finger when it presses on an artery, and is caused by the 

 wall of the vessel, which liacl lost its cylindrical form under the 

 pressure, becoming tense and hard each time that the arterial 

 tension is raised by a systole of the heart, and tending to regain 

 its original form in which all the points in its wall offer an equal 

 resistance to the intense pressure of the blood within. 



The arterial tension on which the pulse depends, is the force 

 expended by the heart, put in reserve by the aorta and large 

 arteries, and regulated by the elasticity of these vessels. If the 

 arterial system were empty, and the heart began to beat, the 

 blood which it sent into the arteries would remain there, very 

 little escaping by the capillaries,! as the arteries would have no 

 tendency to contract and press it on between each systole. As 



* Msbvej, Pht/sioloffie Medicale de la Circulation de Sang. 



t "Wherever I use the word capillaries, I do so in a general sense, and 

 without entering into the question as to the difference between capillaries 

 properly so called, and small arteries, so that if contractile power be denied to 

 capillaries pro^^er, the word may be read " sn;all arteries." 



