OF THE VITAL POWERS. 29 



He considers sympathy as affecting either animal sensibility or 

 contractility, or organic sensibility or contractility. 



Sympathy does not arise from nervous communication-, because 

 it frequently happens that no particular nervous communications 

 of sympathising parts are discoverable, while remarkable ones ex- 

 ist between other parts not disposed to sympathise. * Vegetables, 

 which have no nerves, shew sympathy : if a leaflet of the sen- 

 sitive plant is stimulated bv a burning glass, the whole leaf con- 

 tracts and the foot-stalk drops ; f when the branches of trees 

 feel the warmth of summer, the sap ascends in the roots ; and 

 even in a frost it will ascend from the roots through the stem, if 

 a single branch is introduced into a hot-house. 



Sympathy of animal contractility occurs only when the nerves 

 connecting the affected muscles with the brain., are entire j when 

 they were divided by Bichat, the convulsions in the correspond- 

 ing muscles ceased. The sympathies of the organic functions are 

 never ascribable, as many might imagine, to continuity of sur- 

 face ; for after dividing the oesophagus of a dog, Bichat produced 

 vomiting equally as before, on irritating the fauces. 



(B) Our author here, as below (135), means the pulmonary 

 portion of the pleura, and very properly regards this and other 

 serous membranes, as condensed cellular substance ; that is, as 

 a substance not originally cellular and now condensed, but of 

 the same nature with the cellular membrane, though much more 

 compact. | 



* Consult Whvtt, Observations OH Nervous Distams. Ch. i. 

 f- Sir Gilbert Blanc, Medical Logic, p. 61. 

 J Consult Bichat, TraM ties membranes. 



