PREFACE 



Although the recent appearance of the last volume of De Toni's "Syl- 

 loge Algarum," the "Myxophyceae," has removed some of the greatest 

 difficulties which confront the student of this branch of Algology, yet, 

 with the general literature concerning the blue-green algae in its present 

 state, he has a vexatious problem before him if he attempt to work to 

 any purpose in this group of plants. The original specific descriptions 

 with their accompanying notes and figures, are scattered far and wide, 

 many of them in foreign periodicals and rare works. In general these 

 cannot be obtained in more than a very few of the largest botanical libra'^ 

 Ties. In the United States, at least, there is much need for a work in 

 English, suitable for use as a general hand-book, which shall contain de- 

 scriptions and illustrations of these plants. On the other hand, such a 

 work ought not to be written until a considerable amount of information 

 has been obtained from all parts of the country. An accurate treatise of 

 this sort should be prepared only as a result of general investigation car- 

 ried, on by a large number of workers over the entire area to be covered, 

 at all seasons of the year. For instance, many species have so far been 

 reported from a single locality, which without doubt are growing in pro- 

 fusion in other parts of the country. Without question numerous new 

 species await discovery when the study of the group has become more gen- 

 eral. 



It would seem then that two books need to be written, one as a cause 

 and one as a result of such investigation. If the present treatise proves 

 to be of use as a foundation or ground-work for the second volume, and 

 if it shall be the means of assisting those who are disposed to follow this 

 fascinating branch of microscopic study, the hopes of the author will be 

 realized. The work has been prepared with a view to answering the need 

 of such botanists as do not have access to the special libraries and of 

 others who have not unlimited time to devote to the looking up of litera- 

 ture. Special prominence has been given, in the arrangement of the text, 

 to two features. The student has constantly before him practically all 

 that is known relating to the geographical distribution and the recorded 

 history of each plant in American localities. To quote from Mr. G. S. 

 West, "One cannot emphasize too much the importance of a sound knowl- 

 edge of the geographical distribution of some of the more lowly types of 

 Cryptogams. . . . Such a knowledge, which can only be acquired by the 

 patient labors of the systematist, will throw much light on one of the 

 most interesting of all problems concerned with the later phases of the 

 earth's history, namely, the land-connections of previous periods." It is 

 very much hoped that this volume may encourage interest on the part of 

 general botanists, high school teachers, college students, physicians and 

 bacteriologists in these little plants which are of late coming to be con- 

 sidered of importance even outside of botanical circles. 



In the present volume the author has brought together the specific 

 descriptions of all the blue-green algae so far known to exist in North 

 America and the adjacent regions (including the Arctic Regions, Alaska, 

 Greenland, Canada, Newfoundland, Labrador, the United States, Lower 

 California, Mexico, Central America, the Bermudas, the Bahamas, the West 

 Indies and the Hawaiian Islands). In addition there are figures illustrating 

 many of the species. The figures have been photographed from the original 

 and redrawn. A number of them are original with the author. An atternpt 

 has been made to have the figures all drawn to the same scale which 

 may be an improvement over the ordinary method. Very simple keys are 

 furnished for the families, genera and species. The second paragraph of 

 each specific description contains the names in chronological order of a 

 number of articles and works referring to the species in question. It is 



