IV PREFACE. 



I have preferred giving extracts or full analyses of the 

 writings of the original observers to whom the build- 

 ing up of the Protoplasm theory is due, rather than 

 writing a compendium which would most probably 

 fail to give so accurate or interesting an account of 

 them. Also, as this work is addressed to men of 

 general culture in science rather than to those techni- 

 cally educated, I have entered on the general physi- 

 ology of some parts of the subject more fully than 

 would be required by the latter. But by these means 

 it is hoped that men of general scientific culture may 

 have the opportunity at hand of judging of the im- 

 portant theory attempted, however imperfectly, to be 

 set forth in this book, viz., that every action properly 

 called vital, throughout the vegetable and animal 

 kingdoms, results solely from the changes occurring in 

 a structureless, semifluid, nitrogenous matter now 

 called Protoplasm. 



LIVERPOOL, October, 1874, 



