442 THE LAWS OF ORGANIC 



blood which impedes their functions, but receive that 

 which is improved in its nature, consequently fitted 

 to promote their ordinary functions. 



DXXXIX. We generally find that emetics 

 act as aperients or purgatives ; and CULLEN says, 

 that they are useful only when this consequence 

 follows their employment.* But he, and all other 

 writers on the subject, seem to imagine that this 

 effect arises from the medicines passing from the 

 stomach to the intestines, arid thus acting direct- 

 ly upon the abdominal viscera. This is certainly 

 a very natural supposition as we observe that 

 substances which are almost exclusively purga- 

 tives, appear to operate in this manner. If we 

 carefully examine the true action of emetics on the 

 general systems of the body, and also reflect on 

 the general effects which follow their exhibition, 

 we shall regard the aperient or purgative conse- 

 quence as the result of the improved condition of 

 the mucous membrane, from the influence of those 

 causes that relieve the congestion and stimulate the 

 secernent vessels of the part. 



DXL. Passive hemorrhages are diseases like- 

 ly to be benefited by the use of emetics. 

 There is probably no affection to which the 

 human frame is subject that more evidently 

 arises from an altered state of the blood, or 



* "As inverting the peristaltic motion, vomits are useful in 

 diarrhoea and dysentery ; but, independent of that, they are 

 probably more useful as purging the intestines, occasioning a 

 greater flow of liquors into the intestinal canal.'' Lectures on 

 the Materia Medica, by W. CULLEN, M. D. &c. MDCCLXXII. 



