476 DR T. R. FRASER ON SOME UNDESCRIBED TETANIC SYMPTOMS 



vascular causation of atropia-tetanus, founded on the above arguments. It is true 

 that the demonstration appears to be perfect of great dilatation of the blood-vessels 

 of the skin, muscles, abdominal and thoracic viscera, and several other structures 

 occurring at an advanced stage of atropia poisoning — probably, indeed, this 

 dilatation is contemporaneous with the tetanus — but we have yet to wait for the 

 demonstration of a dilatation of the blood-vessels of the spinal cord during the 

 life of the animal. It is even difficult to believe that the analogous tetanic 

 symptoms of strychnia are due to vascular engorgement, for a frog may be bled as 

 perfectly as possible, and still the subsequent direct application of strychnia to 

 the spinal cord will cause tetanus.* Farther, the discovery of vascular engorge- 

 ment after death from tetanus is insufficient to prove that the production of the 

 tetanus is in any way dependent on that engorgement. It might be urged, with 

 equal reason, that the tetanus is the cause of the spinal engorgement, the 

 mechanical effect of the muscular contractions tending to force the blood into 

 those regions where this effect cannot operate. Besides, there are no good grounds 

 for assuming that an engorged state of the vessels of the cord will necessarily 

 increase reflex excitability or originate tetanic convulsions. 



It is obvious that this question can be solved by direct proof only. An 

 apparent approach to such a solution might appear to be contained in the results 

 of the Experiments in Table III. Tetanus and convulsions rapidly disappeared 

 after copious bleeding. If, however, the blood be freely and abundantly 

 abstracted from a frog in a normal condition, the reflex excitability will be quickly 

 impaired, and, very soon afterwards, it will altogether disappear. 



While, however, we cannot at present accept the view that the tetanic effects 

 of atropia are produced by dilatation of the blood-vessels of the spinal cord, 

 such a method of production is not disproved by any known fact. The question 

 of the exact nature of the causation of atropia-tetanus — in common with similar 

 questions in relation, probably, to every active substance — is, therefore, still open 

 for future research. Meanwhile, by restricting actions to certain organs and struc- 

 tures, we gain an essential advance towards the solution of such problems. 



SECTION D. 

 In this section an attempt will be made to show that the convulsive and 

 tetanic symptoms that have been described in frogs are represented among the 

 symptoms of atropia-poisoning in rabbits, dogs, and other mammals ; and that, in 

 both cases, the causation and special characters of these symptoms, as well as 

 the peculiarities of their occurrence, are the results of exactly the same actions. 



* MM. Martin-Magron et Buisson, " Action Comparee de l'Extrait de Noix Vomique et du 

 Carare," Journal de la Physiologie de l'Homme et des Animaux, 1859, p. 487; Dr A. J. Spence, 

 " On the Mode of Action of Strychnia," Edinburgh Medical Journal, July 1866, p. 50. 



