IX 



CAKDIAC MUSCLE AND NEKVES 



299 



heart itself, and are independent of the connections which unite 

 it by the afferent nerves with the cerebrospinal axis. Galen was 

 aware that the excised heart is able to beat for a considerable 

 time. Under favourable conditions of moisture, temperature, 

 irrigation with blood and other nutrient fluids, and in presence 

 of oxygen, the excised heart, not only of cold-blooded animals but 

 of mammals also, may continue its functions for many hours. 



TheearlierHallerian 

 'doctrine, which saw in 

 this fact a proof of the 

 rhythmic activity of 

 cardiac muscle inde - 

 pendent of nerves and 

 nerve-centres, was dis- 

 allowed after it had 

 been shown by Bichat 

 and J. Mliller that the 

 peripheral sympathetic 

 ganglia function as in- 

 dependent centres in the 

 organs of vegetative life, 

 while Eeniak (1844), 

 Ludwig (1848), and 

 Bidder(1852)discovered 

 a nerve-plexus rich in 

 ganglion cells in the 

 frog's heart. 



Eemak demonstrated 

 the existence of a con- 

 spicuous accumulation 

 of ganglion cells at the 

 mouth of the sinus 

 venosus in the right 

 auricle of the frog's 

 heart. Ludwig de- 

 scribed other ganglionic 

 elements in the region of the interauricular septum. Bidder 

 discovered two other masses of ganglion cells near the auriculo- 

 ventricular groove (Fig. 128). Nothing after these discoveries 

 could be more natural than to ascribe the function of excitatory 

 centres of the rhythmic peristaltic movements of the heart to 

 these intracardiac ganglia. 



Certain well-known experiments of Stannius(1852) gave fresh 

 sanction to this theory of the intracardial ganglionic centres, 

 although they received various and even contradictory interpreta- 

 tions. In his experiments on the frog's heart Stannius discovered 

 two facts which appeared to be of extreme interest : - 



FIG. 128. Interauricular septum of frog's heart. (Bidder.) 

 a., Muscular fibres ; b, endocardium ; c, free border of 

 septum ; d, d, ventricular walls ; e, f, right and left 

 branches of cardiac vagus, with partial decussation ; h, h', 

 anterior and posterior nerves to septum, with numerous 

 ganglion cells, particularly at points k, k' ; I, ?', ganglia 

 near the auriculo-ventriculur border (Bidder's ganglia). 



