209 



small lake is better than a large lake, because the unknown elements can l)e re- 

 duced to a smaller number. 



We have attempted to collect specimens of the higher creatures in such 

 numbers and sizes, that had we collected all the specimens in the lake, our results 

 would not be different. How far we have succeeded in this remains to be seen. 



The main object of the Station is the study of the variation of the non-migra- 

 tory inhabitants. I may be permitted to quote here the plan as stated in the 

 •circuliir issued by the Station last spring. 



The main object of the Station will be the study of variation. Foi' this pur- 

 pose a small lake will present a limited, well circumscribed locality, within which 

 the difference of environmental influences will be reduced to a minimum. The study 

 will consist in the determination of the extent of variation in the non-migratorv ver- 

 tebrates, the kind of variation, whether continuous or discontinuous, the quantita- 

 tive variation, and the direction of variation. In this way it is hoped to survey 

 a base line which can be utilized in studying the variation of the same species 

 throughout their distribution. This study should be carried on for a series of 

 years, or at least be repeated at definite intervals to determine the annual or 

 periodic variation from the mean. A comparison of this variation in the same 

 animals in other similarly limited and well circumscribed areas, and the correla- 

 tion of the variation of a number of species in these areas will demonstrate the 

 influence of the changed environment, and will be a simple, inexpensive substi- 

 tute for much expensive experimental work. 



For this work the situation of Lake Wawasee, surrounded as it is by other 

 lakes, some of them belonging to other river basins will be admirably adapted. 



In connection with this study of the developed forms, the variation in the de- 

 velopment itself will receive attention. For instance the variation in segmenta- 

 tion, the frequency of such variation, and the relation of such variation in the 

 development to the variation in the adult, and the mechanical causes affecting 

 variation. 



This plan will be modified as our knowledge grows and our experiences dictate. 



PART I. THE LAKE AS A UNIT OF ENVIRONMENT. 



Introductory. — A lake is a depression in the ground filled with water more 

 or less stagnant. 



A glance at a good map of North America will show the following peculiar- 

 ities in the distribution of lakes : 



I. A large number of lakes are found in Florida. 

 (14) 



