117 



sitive part, may excite the spinal cord, and produce a reflex ac- 

 tion, we are authorised to consider all the movements taking place 

 as reflex actions. An excitation may have come to the spinal 

 marrow from the bladder, from the bowels, from the lungs, (in 

 which worms are almost always found in the cold seasons, i. e. 

 at the time these phenomena are generally observed,) etc. 



As to the spontaneity of action in muscles, I have tried to 

 prove ia a preceding article that it is a mere and false appear- 

 ance.* I will prove hereafter that the cause of the apparently 

 spontaneous contractions of the heart, is the same as that of the 

 like contractions in other contractile tissues. 



The physiologists who maintain that the beatings of the heart 



* Carpenter says that the action of the uterus, as it shows itself, " not 

 merely in the final parturient effort, but in local contractions that frequently 

 occur during the latter months of gestation, (simulating the movements of 

 the foetus,) are more satisfactorily accounted for by considering them as a 

 discharge of accumulated power, than in any other mode." I will try to 

 prove elsewhere that for the uterus, as well as for any other contractile 

 tisue, there is no spontaneous action. The uterus, in pregnancy, becomes 

 more and more irritable every day, and when its irritability has arrived at 

 a very high degree, then the slight excitation produced by the carbonic 

 acid normally contained in the blood is sufficient to put it in action. When 

 the contractions have begun, they are very much increased by a reflex ac- 

 tion. Every contraction is accompanied by a galvanic discharge on the 

 nerves in the neighborhood of the muscular fibres which contract, and the 

 sensitive nerves being thus excited, it results, 1st, that a pain is felt, the 

 degree of which is in proportion to the degree of any contraction, and 

 therefore with the degree of galvanic discharge ;f 2d, that the spinal mar- 

 row is excited, and produces reflex movements in the uterus. Now, the 

 more these reflex contractions are energetic, the more they are induced to 

 take place again, on account of the galvanic discharge which accompanies 

 them. So that there would be a constant increase in the intensity of the 

 contractions if there were not four limits to them. 1st, there is no 

 galvanic discharge when the muscular fibres are contracted; it is only 

 at the time they are contracting that this discharge takes place ; 2d, the 

 primitive cause of contraction, the excitation of the muscular tissue, by car- 

 bonic acid, diminishes much during the contraction, because the caliber of 

 the small blood-vessels is much diminished, and the blood expelled from 

 them ; 3d, every contraction of the uterus diminishes the degree of its irri- 

 tability ; 4th, the reflex power of the spinal cord becomes exhausted, or at 

 least diminished. 



t See, on this subject, my paper in the Comptes rendus de la Soci4te de Bologne, en. 1850, t. ii 

 p. 172. 



