SECT. XII. 2. OF STIMULUS AND EXERTION. *i 



contractile fibres, owing to the want of its being 

 perpetually expended, or carried away, by their 

 ufual unremitted contractions. And on this ac- 

 count thofe inufcular fibres become afterwards ex- 

 citable into their natural actions by a much weaker 

 ftimulus ; or into unnatural violence of action by 

 their accuftomed ftimulus, as is feen in the hot fits 

 of intermittent fevers, which are in confequence of 

 the previous cold ones. Thus the minute veifels of 

 the fkin are conftantly flimulated by the fluid mat- 

 ter of heat ; if the quantity of this iiimulus of 

 heat be a while diminished, as in covering the hands 

 with fnow, the vefleis ceafe to act, as appears from 

 the palenefs of the fkin ; if this cold application 

 of fnow be continued but a mort time, the fenfo- 

 rial power, which had habitually been fupplied to 

 the fibres, becomes now accumulated in them, ow- 

 ing to the want of its being expended by their ac- 

 cuftomed contractions. And thence a lei's ftimulus 

 of heat will now excite them into violent contrac- 

 tions. 



If the quiefcence of fibres, which had previoufly 

 been fubjecl: to perpetual ftimulus, continues a lon- 

 ger time ; or their accuftomed ftimulus be more 

 completely withdrawn ; the accumulation of fen- 

 forial power becomes fiill greater* as in thofe ex- 

 pofed to cold and hunger ; pain is produced, and 

 the organ gradually dies from the chemical changes, 

 which take place in it ; or it is at a great diitance of 

 time reftored to action by ftimulus applied with 

 great caution in frnail quantity, as happens to fome 

 larger animals and to many infects, which during 

 the winter months lie benumbed with cold, and are 

 faid to fleep, and to perfons apparently drowned, 

 or apparently frozen to death. Snails have been faid 

 to revive by throwing them into water after having 

 been many years fhut up in the cabinets of the 



curious 5 



