PREFACE 



THE following work is the outcome of a series of observations 

 commenced at Leipzig in 1894, continued in Birmingham 1897- 

 1898, and during a two years' stay in Oxford (1898-1899), but 

 not completed until 1902 in Birmingham. For convenience, the 

 Physics (including Chemistry) and the Physiology of protoplasmic 

 movement are arranged in separate chapters, although any such 

 division is entirely arbitrary. Under the first heading those 

 phenomena of protoplasmic movement are discussed which can 

 be directly referred to physical and chemical causes, whereas 

 under ' Physiology ' we deal with those ' vital ' phenomena which 

 cannot as yet be thus resolved. The work on which the latter 

 chapter is based was mainly carried out at Oxford, but almost all 

 the purely physical work has been done in Birmingham, and 

 a part of the latter could not have been accomplished had 

 not Prof. Poynting kindly placed the resources of the Physical 

 Department of Birmingham University at my disposal. I must 

 also record my indebtedness to Prof. Vines, Prof, Gotch, and 

 Sir Oliver J. Lodge, for various suggestions and criticisms. 



An abstract of this paper was read to the Royal Society in 

 February of the present year, and it is owing to the generous 

 financial aid accorded by the Society that I am able to publish 

 this work as a separate treatise. 



BIRMINGHAM, December, 1902. 



