68 



THE AMElilCAN MONTHLY 



[April, 



Foreign methods find a place only 

 so far as they have been published 

 in works known in Germany, but I 

 think but little has wholly escaped 

 us, and corrections and additions will 

 be gladly received. ^ 



\_To be continued^ lit ^ 



Pi'OTisioiial Key to Classification 

 of Algae of Fresh Water. — I. 



BY THE EDITOR. 



The classification of the algae of 

 fresh water is still in a very unsatis- 

 factory condition, when viewed from 

 a scientific standpoint, for the reason 

 that there still remains so much to be 

 learned about the methods of repro- 

 duction and development. No doubt 

 the only scientific classification possi- 

 ble must depend, to a greater or less 

 extent, upon the methods of sexual 

 reproduction. Not that these pro- 

 cesses as observed will serve as a 

 universal and only indication of the 

 relationship or dift'erentiation of fam- 

 ilies, genera and species, but that they 

 must form a basis of classification 

 which shall bring together forms that 

 are genetically connected. It is not 

 sufficient to know how reproduction 

 in a given plant is eftected, but it be- 

 comes also necessary to know the 

 significance, in the genetic history 

 of the plant, of the phenomena ob- 

 sei'ved. For example, in the family 

 zygnemaceas there are various pro- 

 cesses of conjugation between neigh- 

 boring cells. It becomes necessary 

 to trace this method of conjugation 

 downward until we can discover its 

 most primitive manifestation, and 

 then to follow its various modifica- 

 tions until we can determine the 

 course of its development. We shall 

 then be able to understand the true 

 relation between the different genera 

 of the family, and also to assign the 

 family itself to its proper jiosition 

 among the other families of algae. 

 At present this is not possible ; and 

 whoever attempts to improve upon 

 the classification already sanctioned 

 by continued usage, if by no greater 



authority, must be prepared to devote 

 years of constant study to the work. 



It is no new system, therefore, that 

 will be brought forward in these arti- 

 cles. We cannot even promise that 

 they will be in all respects fully up 

 to the times, for much of the litera- 

 ture which we would wish to consult 

 is not at present available. However, 

 the work is offered in the belief that 

 it will prove useful to many readers 

 who are sometimes puzzled to make 

 out the distinctions between the gen- 

 era as usually described in books. 

 Distinctions which those who are fa- 

 miliar with alg£E recognize imme- 

 diately — by what seems a kind of 

 intuition, but is really the result of 

 familiarity with the different genera 

 which permits one to instantly recog- 

 nize many of them at a glance — are 

 not readily picked out from the de- 

 scriptions usually given. It is to aid 

 those who are not acquainted with the 

 subject that this work is compiled 

 from notes and observations made by 

 the author in the course of reading as 

 well as in the study of fresh specimens. 

 It does not purport to be more than a 

 provisional ke}' — a sortof original draft 

 to serve as an outline and guide for 

 future work of a more thorough and 

 comprehensive character. 



It is only after long consideration 

 that we have concluded to follow, in 

 a general way, the arrangement of 

 Rabenhorst's ' Flora Europaea Alga- 

 rum.' This we have decided to do 

 in view of the fact that it will doubt- 

 less be more readily used by the be- 

 ginner in this study, having reference 

 to either Rabenhorst's work, or to the 

 beautifully illustrated work ' British 

 Fresh-Water Algae by M. C. Cooke,' 

 than any more scientific system that 

 might be proposed. 



The system serves very well for the 

 study of the fresh-water species by 

 themselves, but when it is desired to 

 study the algic as a whole, including 

 the marine forms, and to indicate the 

 systematic position of algie among 

 the cryptogams, it is far from satis- 

 factory. 



