30 MICHIGAN ACADEMY OF SCIENCE. 



1st.: The prevalence of sand along the entire shore line, which prevents 

 the starting and growth of young plants, on account of its sterile and 

 movable nature; 2nd.: The rapid slope of the bottom in most places 

 into deep water, which would tend to make the littoral zone very narrow, 

 and brings it into the part of the shore line most acted on by waves; 3rd.: 

 The prevalence of swift currents and strong high waves, which keep the 

 sand in motion and prevent the formation of shoals of finer materials. 

 That there is a flora of considerable extent in Lake Michigan is shown by 

 the fact that Mr. L. X. Johnson reports finding bushels of Nostoc pruni- 

 forme along the southern shore of the lake and says that he has seen it 

 in ridges two to four feet wide and six to eight inches deep. In such 

 shallow estuaries as the mouth of the Saginaw River where silt is de- 

 posited in abundance, there is often an abundant and varied flora. The 

 determination and study of the plants of the Great Lakes can hardly be 

 undertaken by individuals, but must be done largely at the expense of 

 corporations or government on account of the large expense involved in 

 properly equipping for the study. 



In closing, a few words of suggestion in regard to collecting aquatic- 

 plants may not be out of place. If a boat is accessible it is exceedingly 

 useful in getting about on the water to be investigated, but not essential 

 unless the lake has a shallow slowly sloping bottom. Many plants can be 

 reached from the shore in any case and such collecting as can be done in 

 this way is often satisfactory as to results. Some form of dredge is 

 essential and can be made by fastening a series of hooks into a lead disk 

 about three inches in diameter. Through this an iron rod 5-16 of an inch 

 in diameter and about a foot long, bent to form a small ring at one end, 

 is passed so that the disk is below the center. The hooks are 12 to 14 in 

 number and are all bent toward the same side, projecting about an inch 

 and curving inward about an inch. The rod should project about three 

 inches from the disk at the lower end, so that the end will strike the 

 bottom first. The disk should be made heavier on the side toward the 

 hooks which are best made of steel wire. Another form, the one used by 

 the Michigan Fish Commission is described by Mr. Pieters in his account 

 of the Flora of Lake St. Clair. The rope is attached to the ring, and 

 besides being used as a dredge, the instrument may be used for taking 

 soundings if nothing better is at hand and the water is not too deep. For 

 collecting the lacustrine forms of microscopic plants a small bolting cloth 

 towing net is essential. 



BIBLIOGRAPHY. 



The folio-wins list of publications bearing on the subject under consideration 

 may be divided into three classes: 



1. Plant Catalogues, lists and notes relating to geographical distribution. 



2. Manuals and Monographs. 



3. General Treatises. 



Catalogues and Notes. 



(For this list the author is largely -indebted to Beal and Wheeler's Michigan 

 Flora:) 



1839. Wright. J. Catalogue of the Phaenogams and Filicoid Plants, col- 

 lected on the Geological Survey of Michigan. Legislative Report. No: 23, pp. 17-44. 



1849. Cooley. P." Catalogue of the Plants collected by W. A. Burt in the primi- 

 tive region south of Lake Superior in 184G. Jackson's Lake Superior, pp. 875-882. 



