332 Fresh-water Algce of Canada. 



contained were for the most part both inaccurate and obscure. 

 The minuteness of the objects, their fragile and changing character, 

 together with the imperfections of the microscopes formerly in use, 

 made their study sufficiently formidable, and account for the ne- 

 glect which they met with at the hands of botanists. The improve- 

 ments effected of late years on achromatic microscopes in a 

 great measure obviates the difficulties which were at one time 

 experienced by observers, the result of which is that many have 

 entered into the field, and are prosecuting with much zeal the 

 difficult problems which pertain to the fecundity and growth of 

 these plants. Among the older botanists there was a want of 

 due appreciation of the value of the characters of this minute class 

 of plants founded on their reproductive organs. Appearances 

 were chiefly relied on for distinguishing families, genera, and 

 species, and hence, as might be expected, their classification was 

 very imperfect and arbitrary. The discrimination of these organs is 

 however in accordance with the natural system, regarded as the 

 only legitimate principle of classification. They are now seen to 

 be of more importance for the determination of genera and species 

 than all their other appearances whatever. While many plants are 

 exceedingly alike in other characters, they are yet on examination 

 found to be exceedingly unlike in their modes of reproduction, 

 and in the forms of their reproductive organs. A better system 

 having thus been adopted by modern algologists, it has resulted 

 in a more scientific arrangement, which it is to be hoped the pro- 

 gress of discovery will yet bring to a greater measure of perfec- 

 tion. 



The work which drew special attention to the study of the 

 Fresh-Water Algae, in modern times, was the valuable treatise of the 

 Rev. Jean Pierre Vaucher, of Geneva, entitled " Histoire des 

 Couferves d'Eau Douce," published in 1803.* A knowledge of 

 the different modes of their reproduction was the chief aim and 

 study of this writer. Many of his observations are exceedingly 

 accurate, of great value, and have been confirmed by subsequent 

 research. The figures appended to the work are curious, and, 

 upon the whole, correct. One finds no great difficulty in deter- 

 termining the plants they are intended to represent, and in this re- 

 spect they are not inferior to many of the more artistic represen- 

 tations of modern books. The work is still valuable to the careful 



* A fine copy of this volume is in the McGill College Library, Mon- 

 treal. 



