CHLORAL HYDRAS. 159 



produce deeper and more prolonged sleep, and an appearance 

 of narcosis, the subject being difficult to rouse even by sharp 

 stimulation. Thus far chloral manifestly acts upon the convo- 

 lutions, either directly or through the cerebral circulation, or 

 both ; and is a pure and powerful hypnotic. The larger doses, 

 however, enable us to appreciate its action, like that of chloro- 

 form, on the lower nervous centres. The spinal centres are 

 depressed, whence diminished reflex excitability and relaxa- 

 tion of the muscles. The three great medullary centres are 

 decidedly depressed : respiration becomes slow, irregular, and 

 shallow ; the heart is weakened (but chiefly in another manner, 

 as we shall presently find) ; and the vaso-motor centre is 

 lowered in activity, so that the vessels dilate generally. The 

 peripheral sensory nerves are not specially affected. Neither 

 are the motor nerves, or the muscles themselves, directly de- 

 pressed. 



Upon these several effects of chloral depend at once its 

 value medicinally, and the drawbacks or even dangers which 

 occasionally attend its employment. It is the most rapid, and 

 probably the most powerful, whilst the most pure, of all the hyp- 

 notics, opium not excepted. It is therefore extensively used to 

 produce sleep and soothe the cerebral hemispheres, in conditions 

 of excitement, in insomnia from over- work, distress, maniacal 

 excitement, or despondency, and in the early stages of fevers or 

 febrile diseases, whilst the heart is still strong. It is especially 

 valuable in delirium tremens. In the sleeplessness which 

 attends or is caused by peripheral pain, chloral fails, for an 

 obvious reason ; or if sleep be secured by a powerful dose, the 

 patient wakes to suffering as before. To relieve the severe 

 pain of neuralgia it is totally unfitted. 



Chloral has also been given in the delirium of the more 

 advanced stages of fevers; to relieve the distiess, .l\>i-nnM, 

 and insomnia of cardiac and renal disease ; and in the cough, 

 spasm, and breathlessness attending phthisis, bronchitis, and 

 other respiratory affections. The dangers of the drug in these 

 conditions have been shown by the fatal results which have 

 followed its employment; and the cause of them is obvious. 

 Besides its depressing effect on the medulla, chloral in full 

 doses acts as an intrinsic cardiac poison, slowing and ent'> 

 the heart by diminishing the irritability oi : i. and 



finally arresting it in ventricular diastole. At the same time 

 the blood pressure falls by peripheral paralysis of the 

 walls, as well as from the interference with the vaso-motor 

 centre, the heart, and the respiration; so that altogether the 

 circulation tends to become arrested. Thus the relief to be 

 obtained from chloral in the delirium of fpver where the heart 



