Fresh-water Algal of Canada. 333 



student. It has been largely used and acknowledged by all sub- 

 sequent writers, and forms the basis of the more recent and com- 

 plete volumes of Hassall. Since Vaucher's work was published, 

 in the fiery times of the French revolution, much has been done 

 by both Continental and British botanists in the discovery and 

 classification of new species. Among others may be mentioned, 

 as illustrious for their works and labours, Hugo Mohl, Kutzing, 

 Agardh, Pringsheim, and Chon, in Germany ; with Hooker, Tur- 

 ner, Greville, Harvey, Berkeley, Ralfs, and Hassall, in Britain. 

 These men, eminent in science, have both added to our know- 

 ledge of the Algse, and adorned its literature with works of 

 unquestionable accuracy and beauty. 



Much obscurity has arisen in this department of Cryptogamic 

 Botany, from observers describing plants without reference to their 

 stage of growth. It is impossible that plants treated in this way 

 can be recognized by future enquirers. In no class of plants is a 

 collector more liable to fall into this error than in that of the 

 Fresh-Water Algse. In their several stages of growth, while main- 

 taining a uniform type of structure, they are yet so variable in 

 many of their parts and habits, that, without considerable experi- 

 ence, there is great danger of multiplying species without reason. 

 It has, therefore, been considered the wisest course, by modern 

 algologists, to notice only, or chiefly, those species whose repro- 

 duction has been satisfactorily determined or accounted for. 

 Upon such principles, our classifiction of the Fresh Water Algse is 

 grounded. 



We are not aware that this order of plants has yet been ex- 

 amined or determined in Canada. It has, doubtless, been noted 

 with more or less attention, by several explorers of our botany ; 

 but not to our knowledge has anything yet been published. In 

 the United States, Prof. Bailey is known to have directed some 

 attention to the genera and species of his own country, and, pro- 

 bably, among the specimens of his magnificent herbarium, be- 

 queathed to the Natural History Society of Boston, microscopic 

 or dried illustrations of much value may be found. 



So far as our imperfect examination, during hours of rest and 

 leisure, of the rivers, lakes, streams and waters of Canada, has ex- 

 tended, we have found a rich and varied field of research, possessing 

 all the charms of novelty and beauty, and abounding in won- 

 derful evidences of the Creator's perfections. We can fully en- 

 dorse the remark of Hassall in the introduction to his valuable 



