478 PRINCIPLES OF VETERINARY SURGERY 



modified in volume and structure. It is probable that these 

 instances are cases of coagulation-necrosis. The nuclei pre- 

 sent ill-defined outlines and the nuclear plexus is wanting. 

 The neurogliac cells, augmented in volume^ transgress upon 

 the nerve cells. If these lesions would be absolutely constant 

 and special in tetanus they might be attributed to the com- 

 bination of tetanic toxin with the protoplasm of the neuron. 



When tetanus passes to the chronic form degenerative 

 changes ai^e found in the white matter. Nissl (1897) de- 

 scribed different lesions and admitted that they are similar 

 to those observed from ligation of the aorta and from differ- 

 ent poisons. Courmont, Doyon and Paviot continued the in- 

 vestigations of Marinesco in an endeavor to explain the 

 period of incubation of tetanic intoxication. They utilized 

 the cavy and the dog. They found alterations of the cells 

 of the anterior (inferior) columns of the cord, but subse- 

 quently found them also in the medullary substance of sound 

 cavies. The only alterations of at least some of the medul- 

 lary cells is therefore an action of Nissl's method rather than 

 that of the tetanic toxin. In a cavy, killed when the con- 

 tractions were still local (the posterior paw) the same altera- 

 tions were bilateral and occupied the entire medulla. Their 

 topography therefore did not correspond to the contractions. 

 The relations could not be the relations of cause and effect. 

 In the tetanized dogs haemorrhages were never found and 

 the medullary cells were absolutely sound. 



Nissl's method is accordingly incapable of revealing char- 

 acteristic lesions of tetanus. While this opinion is diamet- 

 rically opposed to that of Marinesco it has been confirmed 

 l)y all subsequent investigations. 



Goldschreider and Flatau have studied nerve cell altera- 

 tions in a large number of poisonings, by Nissl's method, and 

 have concluded that similar clinical phenomena may be ob- 

 served from various lesions and vice versa. The same le- 



