354 PHYSIOLOGY CHAP. 



the external sphincter of the anus is entirely relaxed ; but after a 

 few months (as already shown in Vol. II. p. 372) it regains its 

 tone. It reacts to mechanical traction, to injections of cold 

 water, to induced currents ; it may also recover the rhythmical 

 automatic contractions independent of external stimuli which it 

 manifests after simple division of the cord from the higher centres. 

 From these facts Goltz and Ewald concluded that the anal 

 sphincter, in addition to the cerebral and spinal centres, possesses 

 peripheral sympathetic centres, which possibly lie in the depth 

 of the muscle. 



Unlike the sphincter, which also consists of striated muscle, 

 all the striated skeletal muscles atrophy. First they lose their 

 faradic, next their galvanic excitability, lastly, they become 

 inelastic and are reduced to bundles of connective tissue. The 

 bones also alter and become brittle. The digestion, which is 

 disturbed during the first days, becomes normal again in the 

 course of a few weeks. Defaecation takes place regularly once or 

 twice a day, and the faeces are natural in appearance. The urine 

 is clear, free from sugar and albumin. The bladder, which is 

 paralysed for the first days, gradually recovers its functions, and 

 after a few months evacuates the urine collected in it periodically 

 and spontaneously, and when evacuation has taken place the 

 animal remains dry for hours. 



A pregnant bitch, a few hours after extirpation of 94 cm. of 

 cord, gave birth to five puppies, one of which was left to her to 

 suckle, which she did perfectly. The puppy sucked all the 

 mammae in turn, and even the last pair, which were entirety 

 deprived of spinal innervation, yielded an abundance of milk. 



The tone of the blood-vessels in the dog that has lost its cord 

 recovers completely in a few days. The temperature of the 

 denervated posterior limbs becomes the same as that of the 

 anterior, which are still innervated by the spinal nerves from the 

 cervical region. From this it can be seen that the vascular tone 

 does not depend exclusively upon the bulb and cord, as was 

 formerly supposed, but that even under normal conditions the 

 sympathetic ganglion system must have an enormous influence 

 over it. 



One sciatic nerve was divided in a dog that had lost the 

 luinbo-sacral part of its cord ; at first there was a marked difference 

 in the diameter of the vessels and the temperature of the paralysed 

 hind-limbs, but after a few days these differences disappeared. 

 On stimulating the skin of the posterior part of the cordless 

 animal, it is not possible reflexly to influence the vessels at remote 

 parts of the skin, but all stimuli have the same local effect in the 

 posterior as in the anterior part of the animal. - Unipolar ex- 

 citation by induced currents produces pallor of the prolapsed 

 mucosa of the rectum, and heat and cold affect the cutaneous 



