PREFACE. 



The following Essay contains the results of an 

 investigation which has occupied my attention for 

 some time, subject, however, to the interruptions 

 necessarily connected with professional life. They 

 have for the most part already appeared in Papers 

 published on various occasions, viz. in the Philo- 

 sophical Transactions, and the Proceedings of the 

 Royal Society of London, the Philosophical Magazine, 

 the Edinburgh New Philosophical Journal, and the 

 Transactions of the Cambridge Philosophical Society, 

 but they are now collected and published in a more 

 connected form, with a hope that they may lead to 

 future inquiries. 



Objections might be raised to the title of this 

 Essay, Organic Polarity. The results of these in- 

 vestigations lead me to consider it as the most appro- 

 priate. It was not selected as the original title to 

 my Papers, but the conclusions that I have arrived 

 at induce me to believe that we have to deal with 

 polar forces, since there can be no doubt that some, 

 if not all, of the organic actions which take place in 

 the living body are accompanied with the mani- 

 festation of electrical action. I might have entilied 



