INTRODUCTION. 



"Histoire cles Conferves d'Eau Douce," admirable, when the 

 epocli at which it was undertaken, and the means at his disposal, 

 are considered. " I wish," he says, at p. 8., " that those who 

 love Botany may see what are our riches in this respect, and 

 what 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 more 

 rapidly studied. If this work excites the attention of the 

 public, there should appear on all sides observations on new 

 Conferva and there will be announced, perhaps, productions 

 more singular than those which I describe. This taste for 

 research will not be confined to this one genus, but it will 

 extend to other neighbouring genera, which equally require 

 to be studied ; and this beautiful part of Botany will be in- 

 sensibly drawn from the confusion in which it has for so long 

 a time been found." 



An additional reason why the knowledge of the freshwater 

 Algce, and particularly the Confervoid division of that tribe, 

 should for so long a time have remained in such a confused 

 and imperfect state, consisted in the want of a due appreciation 

 of the value of the characters founded on their reproduction, 

 these being of more importance, in the establishment of the 

 different families, genera and species, than all the other signs 

 and characters derived from attention to other conditions and 

 appearances of these plants. To a right appreciation of the 

 importance of attention to the reproduction of the Conferva 

 it is that the superiority of Vaucher's " Histoire des Conferves 

 d'Eau Douce, " is mainly owing, over other works on the same 

 subject, that close and amiable observer having made and he 

 was the first, and almost the only one to do so a knowledge 

 of their reproduction his chief aim and study. Thus the 

 majority of the earlier observers, and some even of recent 

 date, have deemed it sufficient to describe any plant of this 

 class merely from the appearance which it presented on a 

 first examination, without any reference to the stage of de- 

 velopement or condition of that plant ; and have of course 

 expected that the productions thus imperfectly recorded 

 should have been recognized with facility by subsequent in- 



