740 DR FRASER ON THE PHYSIOLOGICAL ACTION 



paralysed, as frequently happens, reflex movement will, on that account alone, 

 be soon impossible. Experiments in which the heart is so affected are nearly 

 worthless as far as the investigation of the spinal action of physostigma is con- 

 cerned, and it would be needless to detail them. With the object of bringing 

 forward as clear evidence as possible on this subject, I have selected experiments 

 in which the cardiac action was only impeded, and in which it continued after 

 the abolition of reflex power. 



It is well known that strychnia causes an exaggeration of the reflex activity. 

 Whether this is produced by an action on the spinal centre, or by one on the afferent 

 nerves, is yet a question in dispute;* but it is obvious that a substance that 

 diminishes this function at the cord, will also diminish the reflex activity con- 

 sequent on the administration of strychnia, whatever be the special part of the 

 reflex circle affected by that administration. Such a result is produced by 

 physostigma, and therefore, adds to the many proofs of its spinal action. 



Experiment XLIII. 



1 placed a small drop of solution of strychnia (Brit. Pharm.) on the back of a frog. This pro- 

 duced tetanus in four minutes ; when a considerable dose of physostigma extract was inserted 

 into the animal's mouth, the manipulations necessary for which excited a series of violent 

 emprosthotonic spasms. Four minutes after the Calabar bean was exhibited, a decided diminu- 

 tion occurred in the frequency and severity of the convulsions ; and, in nine minutes, they had 

 lost their tetanic character. In forty minutes, it was difficult to excite even a faint reflex 

 movement by pretty strong galvanism of any part of the body ; and, soon after, reflex action had 

 completely disappeared, even when the exposed sciatic nerves were galvanised. 



By comparing the last experiment with one in which the strychnia effects 

 were not interfered with, it is easy to show what part the Calabar bean played in 

 thus interfering with the peculiar action of strychnia. 



Experiment XLIV. 

 A frog was selected of the same weight as the last, and in every other respect as nearly 

 resembling it as possible, and a small drop of solution of strychnia (Brit. Pharm.) was placed 

 on its back. Tetanus occurred in four minutes ; and violent convulsions of a tetanic character 

 followed each other at intervals, and could be excited by the slightest touch, during the next 

 six hours, after which the observations were stopped. 



This evidence may be still further increased, if we produce well-marked para- 

 lysis by physostigma and then administer strychnia without causing its peculiar 



action. 



Experiment XLV. 



A frog was selected of the same weight as those employed in the two preceding experiments, 

 and a dose of extract of Calabar bean was inserted under the skin of its back. This acted with 

 considerable rapidity, so that, in twelve minutes, respiratory and voluntary movements had ceased, 

 and reflex action was sluggish. A small drop of solution of strychnia (Brit. Pharm.) was then 

 placed on a wound made through the skin of the back. Twenty minutes after this, reflex move- 

 ment could still be excited ; but during all this time no tetanic convulsion, nor even exaggeration 



* Marshall Hall, Brown- Sequard, Bonnefin, Martin-Magron and Buisson maintain that 

 strychnia causes tetanus by an action on the spinal cord ; Claude Bernard and Stannius are the 

 principal champions of the opposing theory of its action on the sensory nerves. 



