HEAT AND COLD — MUSCAEIA AND NICOTIA. 457 



raising the temperature sufficiently the heat tetanus is converted 

 into heat rigor. Then no application of cold has the slightest 

 effect in restoring pulsation. 



Not only the effects of heat and cold, but the effect of sepa- 

 rating the venous sinus or the auricles from the ventricle can 

 readily be shown with tliis apparatus, as well as the action of 

 various poisons. The best for the purpose of class demonstra- 

 tion is muscaria. A drop of saline solution containing a little 

 of the alkaloid being placed on the heart, it ceases to beat 

 entirely. If a drop of atropia solution be now added the beats 

 recommence. I have seen them do so on one occasion after 

 they had entirely ceased for four hours. When used for demon- 

 strating the action of poisons the wooden lever should be 

 covered with sealing-wax, so as to allow every particle of the 

 poison to be washed off it, and thus prevent any portion from 

 being left behind and interfering with a future experiment. By 

 attaching a small point to the end of the straw in place of the 

 paper flag, tracings may be taken upon smoked paper fixed on a 

 revolving cylinder. 



