PATHOGENESIS OF TETANY 203 



have modified them in various ways. When we had extirpated the para- 

 thyroids in cats and at the same time had cut the sciatic nerve, immediately 

 below its exit from the pelvis, no hyperexcitability made its appearance in the 

 nerve peripherally from the site of the section; much more did the nerve 

 gradually become excitable to the galvanic current in about the same time as 

 after the section in normal animals. 1 If, however, we first obtain our tetany 

 through parathyroidectomy and then transect the nerve when it had already 

 become hyperexcitable, we find that the hyperexcitability continues for some 

 time, and then only gradually passes through a period of normal irritability 

 (with normal electrical reaction) into the condition of nonexcitability. In 

 some experiments it takes nine days before this condition is reached. From 

 this, in reliance on former experiments of Frohlich and Lowi on nerve-muscle 

 preparations of the octopod Eledona moschata, we have concluded that 

 under normal circumstances the nerve is supplied [loaded, stored, ausladen] 

 from its trophic center, the ganglion-cell, with an as yet unknown, indefinite 

 substance, and that separation from this center is followed by a gradual loss 

 of this supply and by degeneration, and that in tetany there exists an ab- 

 normally high loading of the ganglion-cell or of whole neuron proceeding from 

 it. Biedl had set forward to this experiment the objection that pressure on 

 the nerve below the point of severance can no longer elicit muscular spasm. 

 According to Schlesinger's explanation of Trousseau's phenomenon, however 

 (reflex-process on account of irritation of sensory nerves), nothing else than 

 this is to be expected. That, moreover, no muscular spasm appears any 

 longer in the extremity in question is not remarkable, as every new impulse 

 from the ganglion-cell, which is always storing anew, is lacking. 



Further investigations have shown, moreover, that an association of 

 the ganglion-cells of the spinal cord with higher centers is not necessary to 

 render possible in tetany or to obtain in it the abnormal loading of the 

 ganglion-cells. Already Munk had stated that after transection of the 

 spinal cord the spasms in the paralyzed hind-extremity persisted, and 

 Horsley and Lam have since ascertained that after extirpation of the cortical 

 motor areas on one side, the tetany may persist on the other half of the body. 



Our own investigations showed that after section of the spinal cord in 

 animals suffering with tetany the hyperexcitability in the paralyzed hind- 

 extremities remained exactly as in the fore-extremities until death. BiedVs 

 statement that there appeared in the paralyzed extremities lightning-like 

 contractions and fibrillary muscular twitchings, but that all traces of a toxic 

 rigidity were absent, are in direct contradiction to Hunk's statement and 

 our own. In addition we could most definitely assure ourselves that we 



1 In more recent investigations MacCallum (Journal of the American Medical Association, 19, 

 1912, p. 319) found that the peripheral part of the nerve also becomes hyperexcitable, if it had 

 been cut off before the parathyroid had been excised. I cannot state off-hand the explanation 

 for the divergence of our observations. 



