northern Michigan. In selecting material for this survey, emphasis 

 has been placed on collections from strictly aquatic habitats almost 

 to the exclusion of shore and moist-soil floras. This was done inten- 

 tionally because some line had to be drawn and because the major 

 purpose of the survey was to study the distribution of algae in re- 

 lation to known limnological conditions in the inland lakes of the 

 region. I regret that the study could not include the algae of the soil 

 and subaerial habitats, thereby making a more nearly complete con- 

 tribution to knowledge of algae in the area. The exploration of these 

 terrestrial habitats is an interesting project still awaiting the phycol- 

 ogist. 



Although numerous tow samples were taken from Michigan lakes, 

 only meager attention was given to such collections in Wisconsin, 

 because Wisconsin phytoplankton had been studied by Smith 

 ( 1920, 1924 ) . The major portion of the collections that are the basis 

 for the present list came from the margins of lakes, submerged sub- 

 strates, and from weed beds in shallow bays and ponds. Many 

 species were also obtained from marshes and bogs, especially the 

 Sphagnum (acid) types, which abound in northern Michigan and 

 Wisconsin. 



As often as possible, identifications were made from living mate- 

 rial. Many species in the preserved samples, especially flagellated 

 forms and some Cyanophyta, were disregarded because their taxo- 

 nomic characters had been lost. The preservative used was Tran- 

 seau's Solution, known as Six-Three-One, made with six parts of 

 water, three parts of 95 per cent alcohol, and one part formalin. 

 When 5 cc. of glycerine per 100 cc. of preservative are added to this 

 solution it proves to be especially valuable in preventing complete 

 desiccation of bottled specimens in case of accidental drying. Fur- 

 thermore this preservative is desirable because it produces the 

 minimum amount of plasmolysis and preserves the sheath-character- 

 istics of most blue-green algae. Formalin-aceto-alcohol was also used 

 (formalin 5 cc, glacial acetic acid 5 cc, 50 per cent alcohol 90 cc. ). 

 Each sample was given several examinations, but inasmuch as many 

 vials have a very rich mixture, the list of species for each collection 

 may be incomplete. A number of herbarium specimens have been 

 prepared directly from living material, and some mounts have been 

 made from liquid-preserved collections when their abundance in the 

 sample warranted. All preserved samples are filed at present in my 

 collections. It is expected that the herbarium specimens, to be pre- 

 pared as time and occasion permit, will be deposited, as are some 

 already, in the Farlow Herbarium, the Chicago Museum of Natural 

 History, the New York Botanical Garden, and in my own herbarium. 



IX 



