122 CIRCULATING FLUIDS : 



genesis of tlie blood-corpuscles, then it is distinct from the 

 previous views. Reichert in his work on Development, has 

 said nothing respecting the formation of blood-corpuscles in 

 the adult ; but from a personal communication, I find that he 

 regards the liver as the blood-preparing organ in adults, and 

 the preparation of the blood as the principal function of that 

 gland ; the secretion of bile must then be regarded as a conse- 

 quence of the metamorphosis that occurs during the above process. 



On the forces that circulate the blood. 



The due performance of the functions of circulation and 

 respiration is as essential to the metamorphosis of the blood 

 as it is to life itself. 



Circulation commences in the foetus with the rhythmic 

 movements of the heart. 



Reichert ' has observed in the incubated e^^, that the only in- 

 dependently formed canals for the blood are the great vascular 

 trunks directly connected with the heart; the other blood-vessels 

 are, as it were, excavated by the force of the heart's action on 

 the blood-cells in the loose cellular mass of the early embryo. 



The action of the heart is the primum movens of the cir- 

 culation. Burdach^ observes that the vital action of the heart, 

 which acts mechanically on the blood, and propels it in certain 

 directions and courses, indicates most clearly that the heart 

 comprehends within itself the elements of the circulating 

 power, and that independently of its vital activity, the whole 

 circle of phenomena appertaining to it results from its mere 

 mechanical relations. The cause of the heart's action must be 

 referred to the irritation produced in it by the living blood. 

 Miiller ^ also considers that the blood is chiefly propelled by 

 the rhythmic action of the heart. 



The view taken by Schultz '^ is difi'erent : he considers that 

 the motion of the blood in the living body results from the 

 joint influence of the blood and of the vessels reciprocally 

 acting on each other, whose true nature can only be seen in 

 the vital relations, audits aim in the circle of organic functions. 



R. Wagner^ is inclined to beheve that the blood is propelled 



> Op. cit. p. 142. 2 Op. cit. vol. 4, p. 163. 



3 Op. cit. vol. 1, p. 163. ■* Op. cit. p. 244. 



* Zur vergleichenden Physiologic des Blutes, 1833, p. 70. 



