DAVIS ON FLORA OP LAKES. 29 



tion of the botanists of. Michigan in regard to this field. 1st.: Every 

 effort should be made to complete the filling out of the list of macroscopic 

 species and to work out the limits of the geographical and vertical 

 distribution of each form. 2nd.: A systematic study of the micro- 

 scopic forms, about which practically nothing is known, should be under- 

 taken and carried out. 3d.: The biological interrelations of plants and 

 animals should be fully worked out, for the problem is one of great com- 

 mercial as well as scientific interest, for Michigan is rapidly becoming the 

 banner summer resort of this whole section of the country, and her lakes 

 are attracting a large number of people to their banks, and in part, the 

 fish of the lakes form the attraction. We must know the conditions that 

 are most favorable to animal life in the lakes if the attraction is to re- 

 main a permanent one, for already the fish population of most of them is 

 perceptibly diminished. 4th.: The special problems of distribution and 

 propagation of the mascroscopic aquatic vegetation are well worthy of 

 solution and form an attractive field for investigation. 5th. : Still more in- 

 teresting, perhaps, is the series of questions suggested by the special forms 

 of leaf and stem developed by the submerged aquatics which have never 

 been looked into in connection with American species. 6th.: The study of 

 the modifications presented by the flowers of aquatics to bring about cross 

 fertilization, and to prevent blighting by wind and wave; the means for 

 encouraging the visits of insects have been neglected and even worse in 

 America and should be taken up. 7th.: The various physiological 

 and anatomical changes brought about by the peculiar environment of 

 this whole group of plants can be studied to advantage. These are some, 

 indeed but a few, of the problems in pressing need of solution in connec- 

 tion with the plants of our smaller lakes. Shall we undertake to solve 

 them? One question suggests itself as exceedingly interesting and I 

 would invite the attention of the systematic botanists to it. There is ft 

 variety of species of flowering plants that seem to prefer the cracks of 

 floating logs as a habitat. In it they invariably take a depauperate and 

 starved form which is quite characteristic and undoubtedly a number of 

 such forms could be made into variety minors, etc., that would stand 

 criticism quite as well as many we already have. The problem of the 

 flora of the Great Lakes is of such magnitude and importance that I 

 hesitate to approach it with my present lack of knowledge. A gentleman 

 entirely familiar with the subject, a botanist of more than national reputa- 

 tion called my attention to the fact that while the ocean, bays and inlets 

 and even the exposed coasts teemed with vegetation, the great lakes were 

 barren of it. My home was on the Atlantic coast and I would modify the 

 above statement in regard to the ocean by adding the words, ''except 

 where there is sand." The sand coast is entirely without vegetation and 

 is nearly without animals. My only experience along the Great Lakes 

 was a year spent in Chicago, where I noted the lack of visible vegetation 

 in the waters of Lake Michigan at that point, but had my attention repeat- 

 edly called to the fact that the artificial ponds in Jackson Park, which 

 were directlv connected with the lake bv a wide canal, were constantlv 

 being dredged out by the gardener to prevent their being overgrown, a 

 fact that indicated that the waters of the lake were not lacking in plant 

 food. Since I have given more thought to the matter I am inclined to 

 ascribe the lack of littoral vegetation in these lakes to three causes: 



