PREFACE. V 



In such considerations may be found the leading 

 motive for this course of lectures. While directed in 

 the main to the higher needs of investigators, they 

 deal, as a rule, with subjects of present, and quite gen- 

 eral interest to beginners ; and considerable pains has 

 been taken to put them in a form that would be readily 

 understood by such readers. In general, it may be said 

 that the authors undertake to set forth what has been 

 accomplished in their special fields of research, to give 

 the conclusions of the best work and thought, to point 

 out general bearings, and to state the problems that 

 await solution. 



Obviously, such a course of lectures admits of un- 

 limited development. Those here offered may serve to 

 emphasize our need, and perhaps may contribute some- 

 thing towards the eventual realization of that more 

 perfect organization which we look for in the establish- 

 ment of a permanent station with an endowment equal 

 to our great opportunities for marine biological research. 



C. O. WHITMAN. 



