PRODUCED BY ATROPIA IN COLD-BLOODED ANIMALS. 477 



There can be little doubt that, in many cases, the convulsions that appear 

 during poisoning by atropia in man, dogs, rabbits, and other mammals, are 

 due chiefly to asphyxia, caused by impairment of the functions of the cerebro- 

 spinal nervous system. These convulsions are, however, due also to a special 

 and primary stimulant action of atropia on the spinal cord. The latter method 

 of production has been recognised by observers who were fully alive to the possi- 

 bility of such symptoms being produced by asphyxia alone* Several experiments 

 in dogs have satisfied me— so far as evidence short of direct demonstration can 

 do so— that this is the case ; for, after the administration of doses that were 

 about the minimum fatal, I have, on several occasions, observed a condition of 

 combined unconsciousness, partial paralysis, and exaggerated reflex activity con- 

 tinue for more than twenty-four hours, while, during a considerable portion of 

 this time, the respirations were of fair character. 



The remarkable position that the convulsive symptoms occupy in frogs — 

 occurring subsequently to either a partial and short, or a complete and protracted 

 paralysis of the cerebro-spinal nervous system — at first sight appears to lend but 

 little support to the assertions that atropia has a primary spinal-stimulant action 

 in mammals, and that atropia-convulsions are caused by the same action in both 

 frogs and mammals. It is, however, necessary to remember, that in atropia the 

 amount of spinal-stimulant is in all animals less than the amount of paralysing 

 action, and that paralysis, compared with spinal-stimulation, is more rapidly pro- 

 duced by atropia in frogs than in mammals. 



The first of these propositions — that the amount of spinal-stimulant is in 

 all animals less than the amount of paralysing action — is founded on the fact, 

 that the principal symptoms produced by an aggregate of various doses are those 

 of paralysis. Thus, in frogs, the smallest doses that affect motricity cause slight 

 paralysis without any obvious symptom of spinal-stimulation (Experiment IV. 

 Table I.); somewhat larger doses cause more decided paralysis, with slight symp- 

 toms of spinal-stimulation (Experiments V. and VII. Table I.); still larger doses 

 cause complete paralysis, and violent symptoms of spinal-stimulation (Experi- 

 ments XV. XVI. XVII. XVIII. XIX. XX. XXL, &c. Table I.); and doses so large 

 as to produce death rapidly, cause complete paralysis without any manifestation 

 of a spinal-stimulant action (Experiments XLII. XLIIL, &c. Table I.) In 

 mammals, the symptoms are in like manner confirmatory of the proposition. We 

 may safely refer to almost every investigation in which different doses of atropia 

 have been administered to animals of the same species ; but the following short 

 account of two experiments, which are described with minute detail in an inge- 



* Meuriot, Joe. cit. p. 98, &c. Brown-Sequard, "Lectures on the Diagnosis and Treatment of 

 Functional Nervous Affections," 1868, p. 66. Both authors account for the increased excitability of 

 the spinal cord by dilatation of blood-vessels — a method of causation which, I believe, cannot be 

 established by any evidence that we at present possess. 



VOL. XXV. PART II. 6 G 



