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INTRODUCTION.

“Histoire <tcs Conferves d’Eau Douce,”—admirable, when theepoch at which it was undertaken, and the means at his disposal,are considered. “ I wish,” he says, at p. 8., “ that those wholove Botany may see what are our riches in this respect, andwhat are the discoveries reserved to their perseverance :now that the way is open, more persons should engage them-selves in the study of these objects, and they should be morerapidly studied. If this work excites the attention of thepublic, there should appear on all sides observations on newConferva and there will be announced, perhaps, productionsmore singular than those which I describe. This taste forresearch will not be confined to this one genus, but it willextend to other neighbouring genera, which equally requireto be studied; and this beautiful part of Botany will be in-sensibly drawn from the confusion in which it has for so longa time been found.”

An additional reason why the knowledge of the freshwaterAlga, and particularly the Confervoid division of that tribe,should for so long a time have remained in such a confusedand imperfect state, consisted in the want of a due appreciationof the value of the characters founded on their reproduction,these being of more importance, in the establishment of thedifferent families, genera and species, than all the other signsand characters derived from attention to other conditions andappearances of these plants. To a right appreciation of theimportance of attention to the reproduction of the Confervait is that the superiority of Yaucher’s “ Histoire des Confervesd’Eau Douce, ” is mainly owing, over other works on the samesubject, that close and amiable observer having made—and hewas the first, and almost the only one to do so — a knowledgeof their reproduction his chief aim and study. Thus themajority of the earlier observers, and some even of recentdate, have deemed it sufficient to describe any plant of thisclass merely from the appearance which it presented on afirst examination, without any reference to the stage of de-velopement or condition of that plant; and have of courseexpected that the productions thus imperfectly recordedshould have been recognized with facility by subsequent in-