14 NATURE AND RELATIONS OF BIO-ECOLOGY 



For the reasons given above, it appears desirable to consider here 

 only such contributions as are based intentionally upon the biotic 

 community, supply quantitative materials for it, formulate new prin- 

 ciples, or apply those already proposed by the plant ecologist for 

 land. The details of these, moreover, are considered in the chapters 

 to which they pertain, along with the studies set aside for discussion 

 there. However, no sharp line can be drawn between them, and the 

 arrangement subserves the necessary requirements of brevity nearly as 

 much as it docs that of historical development. 



Forbes (1887). Forbes was apparently the first to express clearly 

 the unity inherent in a lake. He regarded it as a chapter out of 

 the history of primeval time. The conditions in it are primitive and 

 the forms of life relatively low and ancient, while the system of 

 organic interactions by which these influence and control one another 

 has remained substantially unchanged since a remote period. The 

 animals of such a body of water are remarkably isolated — closely 

 related in all their interests but very largely independent of the land. 

 A single body of water exhibits a far more complete and independent 

 equilibrium of organic life than any land area. It is an islet of older 

 and lower life — a little world within itself, a microcosm in which all 

 the elemental forces are at work and the play of life goes on in full, 

 but on a scale so small as to be easily grasped. 



Nowhere else is the coherence of such an organic complex so clearly 

 visible; whatever affects one species must sooner or later have some 

 influence on the whole community. One thus perceives that it is im- 

 possible for one form to be completely out of relation to the others, 

 and realizes the need for a comprehensive view of the whole as 

 requisite to the understanding of any part. With the black bass, for 

 instance, one learns but little by limiting himself to this species; he 

 must study also the species upon which it depends and the factors 

 that control them. It is likewise necessary to determine the course 

 and outcome of competition, as well as the conditions involved. When 

 this has been done, the investigator will find that he has run through 

 the whole complicated mechanism of aquatic life, both animal and 

 vegetable, of which the bass forms but a single element. 



From the title alone, "The Lake as a Microcosm," it may well seem 

 that the author intended to include the habitat in the entity, but this 

 appears not to have been the case, in view of his references to the 

 "organic complex" and to the "equilibrium of organic life." 



Cleve (1897). As has been previously stated, for a number of rea- 

 sons the study of plankton, especially the microplankton, had, more 

 or less necessarily, a biotic character from the beginning. This is 

 chiefly because the organisms concerned represent both the plant and 

 animal kingdoms, but it is also due to the quantitative nature of hauls, 

 as well as to the strikingly seasonal and annual cycles involved. The 

 situation is perhaps best exemplified by the pioneer essay of Cleve to 

 distinguish types or communities of phytoplankton in the Atlantic 

 and its ti'ibutaries, based for the most part upon one or more preva- 

 lent species of diatoms. The six communities recognized were termed 

 tripos-, styli-, chaeto-, desmo-, tricho-, and sira-plankton, the name 



