Vlll PREFACE 



The Physiological Station, endowed by the State 

 and the City of Paris, has afforded in this respect 

 unique opportunities, and there, with new appliances, 

 the following investigations have been for the most 

 part carried out. 



We shall see by a variety of instances to what ex- 

 tent the older methods are applicable for the analysis 

 of certain phenomena, and what progress has been 

 achieved by chronophotography. 



Each chapter is nothing more than an outline, for 

 any attempt to fill in the details of any section would 

 monopolize the time and attention of a trained 

 specialist. 



In a few instances such an attempt has been made, for 

 geometricians, hydraulic engineers, naval and military 

 men as well as artists have all had recourse to this 

 method, and at last naturalists have interested them- 

 selves in the matter. It is more especially to this 

 latter class that we dedicate our work, since it appeals 

 to their particular ambition, namely, that of discover- 

 ing among the phenomena of life something that has 

 hitherto escaped the most attentive observation. 



