6o INTERNAL SECRETION 



severed also the anterior crural nerve and the obturator nerve. 

 Moreover, if the sciatic nerve is not divided high up, at the place 

 where the plexus emerges from the pelvis, communication with 

 the centre is not entirely cut off, and hence the persistence of 

 the nervous irritability. In view of this fact, the explanation 

 given by the authors appears superfluous. This explanation is 

 that the increased excitement in tetany is due to the continued 

 abnormal loading of the entire neuron from the trophic centre 

 (the ganglion cell of the anterior cornu) with a substance, at 

 present unknown and not definable ; and that this substance re- 

 mains for a time in the peripheral portion of the severed nerve. 



The relationship of tetany to the spinal cord is best studied 

 in animals in which the cord is severed at the sixth or eighth 

 dorsal vertebra. The parathyroids may be removed at the same 

 time, or subjects with tetany may be employed ; the results in 

 either case will be identical. After resection of the cord, there 

 will be complete flaccid paralysis of the hinder part of the body 

 with, at first, normal or exaggerated reflexes. If tetanic move- 

 ments either remain or reappear, the whole of the paralysed 

 portion of the body will show, in addition to slight fibrillary 

 contraction, rapid, lightning-like spasms of large muscular areas, 

 which resemble voluntary movements. It as an extraordinary 

 thing to see the paralysed hinder extremities contract so rapidly 

 and so violently that they appear to make running movements. 

 But there is a marked difference between the behaviour of the 

 fore and hinder parts of the body and this becomes particularly 

 suggestive as the muscular spasms work up to the height of a 

 tetanic seizure. The fore part of the body is affected with violent 

 clonic muscular contractions which are interrupted by tonic con- 

 tractions, the muscles being rigid in the intervals. The hinder 

 part of the body is much less affected. The muscles are relaxed, 

 there are fibrillary tremors, and single coarser lightning con- 

 tractions ; movements resembling running movements occur, but 

 there is no trace of tonic rigidity. From these results it appears 

 highly improbable that the seat of the tetanic changes is in the 

 ganglion cells of the anterior cornua. MacCallum thinks that the 

 site of hyper-irritation is in the higher motor neuron, probably 

 just below the cortex. 



Not enough attention has been given to the part played in 

 tetany by the higher portions of the brain, the cerebrum and 

 cerebellum. Horsley and Lanz are frequently cited as having 

 proved that extirpation of the motor areas of the cortex of one 

 side does not affect tetany of the other. But if the subjects are 

 closely watched, it will be seen that the half of the body which 

 has lost its motor centre is affected much more intensely than 

 the other, and that during the tetanic seizures the tonic muscular 

 rigidity of this side is very pronounced. During remission, on 

 the other hand, whether spontaneous or, as in my experiments, 



