192 AN AMERICAN TEXT- HOOK OF PHYSIOLOGY. 



Blood of Various Animals. — Roy gives some data as to the effect on the 

 froe's ventricle of the blood of various animals. The blood of the various her- 

 bivora (rabbit, guinea-pig, horse, cow, calf, sheep), as well as that of the pigeon, 

 were found to have nearly the same nutritive value in each case. That of the 

 dog, of the cat, and more especially of the pig, while in some instances equal in 

 effect to that from the horse or rabbit, were in other examples (from the newly 

 killed animals) apparently almost poisonous. Cyon's early observation of the in- 

 jurious action of dog's blood on the frog's ventricle has already been mentioned. 1 



Regarding the mammalian heart, experience has shown that it is best to 

 supply the heart with blood from the same species of animal. The difficulties 

 attending the use of blood from a different species are seen in the case of the 

 dog's heart supplied with calf's blood. The heart dies sooner; cedema of the 

 lungs takes place, impeding the pulmonary circulation and leading to engorge- 

 ment of the right heart and paralysis of the right auricle ; exudation into the 

 pericardium often seriously interferes with the beat of the heart; and, finally, 

 the elastic modulus of the cardiac muscle is apparently altered, permitting the 

 heart to swell until it tightly fills the pericardium, when the proper filling of 

 the heart is no longer possible through lack of room for diastolic expansion. 



PART IV.— THE INNERVATION OF THE BLOOD- VESSELS. 2 



About the middle of the eighteenth century more or less sagacious hypotheses 

 concerning the contractility of the blood-vessels began to appear in medical 

 literature, but it was not until Ifenle demonstrated the existence of muscular 

 elements in the middle coats of the arteries in 1840 that a secure foundation 

 was laid for the present knowledge of the mechanism by which that contractility 

 is made to control the distribution of the blood. More than a hundred years 

 before, indeed, Pourfour du Petit had shown that redness of the conjunctiva 

 was one of the consequences of the section of the cervical sympathetic, but had 

 called the process an inflammation, in which false idea he was supported by 

 Cruikshank and others; and Dupuy of Alfort had noted redness of the con- 

 junctiva, increased warmth of the forehead, and sweat-drops on ears, forehead, 

 and neck following his extirpation of the superior cervical ganglia in the 

 horse; Brachet, also, cutting the cervical sympathetic in the dog, had gone so 

 far as to attribute the resulting congestion to a paralysis of the blood-vessels. 

 Hut the-e were merely clever -peculations, for the anatomical basis necessary 

 for a real knowledge of this subject was wanting as yet. Henlc furnished this 

 basis, and at the same time reached the modern point of view. ''The part 

 taken by the contractility of the heart and the blood-vessels in the circulation," 

 -aid Henle, "can be expressed in two words: the movement of the blood depends 

 on the heart, but its distribution depends on the vessels." Nor did Henlc; stop 

 here. It was now known that the vessels possessed contractile walls ; it was 



1 See also Bardier: Comptes rend/us Societi de Biologic, 1898, p. 548. 

 'See footnote t<> Part II., p. lis. 



