CONX'LUSION. 445 



of acknowledged skill and powers of observation have even 

 fallen into the error of asserting that a number of distinct 

 species are conditions of one and the same plant. Thus 

 M. G. Thuret, whose papers on the locomotive organs of the 

 spores of the Alga are the most interesting and important of 

 any which have ever appeared on the Algce, has committed 

 this mistake in reference to the Vmicherm, declaring that all 

 the species are states of one and the same production, and 

 comprising them all under the name of Vaucheria Ungeri: for 

 a refutation of this position, see the figures of the species of 

 this genus contained in the ])resent work. Other observers, 

 again, even go further than this, not allowing the Vaucherm 

 to rank as species at all, but stating that they are merely 

 stages in the growth of mosses. Statements of this trans- 

 formation of AlgcE into mosses, &c., are wholly without found- 

 ation, and wholly undeserving of credit. 



The end is drawing near. How strongly are we mortals the 

 creatures of habit and" association ! with what reluctance do 

 Ave quit a place, a companion, or a pursuit with which we 

 have been long connected, and it may be not altogetlier 

 agreeably so ! The prisoner of Chillon felt regret at quitting 

 the prison of which for so many years he had been the soli- 

 tary inhabitant : each of us can call to mind the pain which 

 we have experienced in leaving a companion with whom we 

 have been long associated, even though that companion may 

 not have been really esteemed by us; and I must confess that 

 I cannot banish some feeling of regret at the conclusion of 

 this undertaking, which has for so long a time interwoven 

 itself with my thoughts, notwithstanding that there are several 

 considerations which render the completion of the task a sub- 

 ject of congratulation. 



Although in a few days I shall cease to be occupied with 

 this work, the interest Avith Avhich the subject of which it 

 treats has inspired me will not have ceased. In the fact 

 that I have devoted so much time to its consideration there 

 is no regret : I am still willing to devote more to it ; and I 

 shall gladly at all times avail myself of the correspondence of 

 all or any who may take an interest in the AJgoi, and will 



