ON FIB RILL AR CONTRACTIONS. 193 



induced in the auricle by strong stimulation, the recovery to a normal co- 

 ordinated contraction takes place quickly and easily after the stimulus is over. 

 According to Gley, 1 fibrillar contractions may be induced in the ventricle of a 

 new-born dog upon strong stimulation just as in older dogs, but the ventricular 

 muscle at this stage behaves like the auricular muscle of the adult, and the 

 inco-ordination can pass off easily and give place to regular normal contractions. 

 After the dogs are twenty-nine to thirty-three days old, no such recovery is 

 possible under ordinary conditions. But Porter 2 has shown that even in 

 adult animals the normal contractions may be renewed, provided the nutrition 

 of the muscular substance be restored by perfusing blood of the same animal, 

 at the temperature of the body, through the muscular substance, either by 

 way of the coronary arteries or by way of the vessels of Thebesius, as in 

 Pratt's experiment (cf. p. 188). In many cases the artificial circulation alone 

 will not transform the condition of fibrillation into that of regular co-ordinated 

 beating; it is, however, always possible to obtain this result if the fibrillar 

 contractions are first caused to cease by the application of cold, and then, when 

 the ventricle is quite motionless, the warmed blood solution is sent through 

 its muscular substance, 



Besides electrical stimulation, these fibrillar contractions have been 

 observed as the effect of bromide of potassium in large doses, under 

 conditions of anaemia and other weakening agencies, and exceptionally 

 as the result of the intravenous injection of extract of the suprarenal 

 capsules, 3 the actual cause in this case being probably excessive contrac- 

 tion of the coronary arterioles. It would appear that the fibrillar con- 

 tractions, which occur upon ligature of the coronary arteries, must be 

 ascribed to anemia and not to any stimulation of nerve fibres by the 

 ligature, 4 and it is very instructive to notice the order of sequence of the 

 events which follow ligature of the coronary arteries, according to See 5 

 and Cohnheim. 6 After the arteries have been tied, the first effect is that 

 the ventricle drops beats, i.e. does not respond to every auricular beat ; 

 this partial block between auricle and ventricle is then followed by a 

 complete block, so that the ventricle remains still ; this standstill is then 

 followed by fibrillar contractions of the ventricle. 



These observations suggest very strongly that the condition of 

 fibrillar contraction is brought about by a blocking in the connections 

 between the branching muscle cells of the ventricle itself ; that, in fact, 

 a difference of conductivity takes place in the different portions of the 

 ventricular muscle, owing to anaemia, just as in the tissue of the auriculo- 

 ventricular ring ; in consequence of which contractions travel at different 

 rates, and are blocked at different distances throughout the whole ventricular 

 muscular mass, thus giving the appearance of inco-ordinated contractions, 

 known as fibrillar contractions. That this is the probable explanation 

 of fibrillar contractions follows, it seems to me, from my experiments on 

 the stimulation of a strip of muscle cut from the apex of the tortoise 

 ventricle. In such a strip the very action of the section has of necessity 

 brought about a series of blocking places ; in consequence of this, the 

 single induction shocks applied to one end of the strip at first cause 

 contractions which are limited to the tissue in the immediate neighbour- 



1 Compt. rend. Soc. dc biol., Paris, 1892. 



2 Am. Journ. PhysioL, 1898, vol. i. p. 71. 



'> Oliver and Schafer, Journ. Physiol., Cambridge and London, 1895, vol. xviii. p. 261. 



4 Porter, ibid., 1894, vol. xv. p. 121. 



5 Se"e, Bochefontaine, and Roussy, Compt. rend. Soc. de biol., Paris, 1881, p. 86. 



6 Cohnheim and v. Schulthess Rechberg, Kin-hoic's Archiv, 1881, Bd. Ixxxv. S. 50-3. 



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