26 MICHIGAN ACADEMY OF SCIENCE. 



the aquatic plants are known but from a single station or from two oi 

 three widely distant ones, while comparatively few are known from a 

 large number of stations. Lastly, we may look in vain, with one exception, 

 for contributions of any sort to the knowledge of the myriad forms of 

 Algae and other groups of flowerless plants with which the waters of oui 

 lakes fairly teem. 



It is evident from the foregoing considerations that the botanists of 

 this body have a duty to perform, and as w^e shall have to begin at the 

 foundation, let us look at the field from various standpoints. In a dis- 

 cussion of the flora of our lakes from any point of view, we shall have to 

 place the four great lakes in a group by themselves, because from their 

 great size and depth special conditions which do not obtain in the smaller 

 lakes, have to be considered from their effect on plant life. It is also well, 

 at the beginning of any subject on which it is proposed to make extended 

 investigations, to establish a series of terms whose meaning shall be 

 exactly defined and strictly limited in application, so that there shall be 

 no confusion as the work progresses. Therefore, since American litera- 

 ture contains nothing of general application relating to the plant life of 

 fresh w'ater, in this paper I propose to adopt the suggestions of Haeckel 

 and other German writers in regard to terminology, for the German 

 biologists have, with characteristic energy, already made a number of 

 studies of the life of fresh water lakes. Since the term ''pelagic" has 

 already been applied to those forms of plants and animals which are 

 found freely floating or swimming at various depths in the open ocean, 

 it is suggested by Haeckel that similar forms in our fresh water lakes be 

 called limnetic and that they be divided into auto-limnetic, zono-lim- 

 netic, and bathy-limnetic groups, according as their habitat is the surface, 

 intermediate zones, or the depths of the lakes. For the total swimming 

 and floating population of fresh water lakes the term limno-plankton, as 

 opposed to halo-plankton or simply plankton, for salt water forms. The 

 general adoption of these or equivalent terms will avoid whatever con- 

 fusion might arise from the use of older terms heretofore applied to salt 

 water life-forms. These terms are general, applying to all forms of 

 organisms. These living organisms are animal as well as plant and in 

 the lower orders the line of demarkation is faint and not sharply defined, 

 but it is not necessary to enter into a discussion of the distinction between 

 the two groups here, as we will consider those forms of life which are 

 ordinarily called plants by good authority, as such, leaving disputed 

 groups to be classified later. If botanists had adopted the use of the 

 word protophyta to apply wholly to unicellular plants, it would have been 

 possible to adopt Haeckel's clavssification dividing all plants into pro- 

 tophyta and metaphyta, the former apph'ing wholly to one-celled thi' 

 latter to the tissue forming forms, but at present, usage is opposed to such 

 a scheme. For our puq^ose it will be well to separate the visible and 

 larger from the invisible and smaller forms, into macroscopic and micro- 

 scopic. The macroscopic plants are of two types, the amphibious and the 

 truly aquatic. The amphibious plants may be farther subdivided into 

 those forms which grow habitually in the water on the edge of the marshy 

 border, the truly littoral forms, and those which grow in the marsh itself, 

 and are capable of living through a considerable period of submergence 

 during their growing season, the palustrine forms. 



