RECENT IIESEARCIIES IN TIlE BIATOMACE^. 241 



acquainted with Heiberg's book, ' Ue Dauske Diatomeer.' '^ 

 The labour of acquiring a knowledge of the Danish language 

 will be well requited by the profit and pleasure they cannot 

 fail to derive from its perusal. 



A patient and careful examination of the several species of 

 Diatoniacece in the direction indicated by Dr. Pfitzer, even in 

 the hands of men much less competent than he is, can scarcely 

 fail to contribute most important additions to ovir knowledge 

 on the subject. At the same time, there is reason to doubt 

 that a more satisfactory system of classification than we have 

 at present is likely to be established. A ' considerable 

 number of the known species of Diatoniacece are fossil, and 

 for this reason are beyond the reach of such observations ; 

 but if these researches contribute to verify in any degree the 

 correctness of the present system of classification, to make 

 clear what remains doubtful, or to rectify mistakes that may 

 have been made, the labours of Dr. Pfitzer will have proved 

 eminently successful. 



Deferring my remarks on the direct results of Dr. Pfitzer's 

 observations to my next paper, I shall now refer to two 

 matters of interest noticed in the introduction. 



The name DiaiomacecB has been used by nearly all ihc 

 more recent authors to designate the group. Rabenhorst, in 

 his more recent work, has adopted the name Diatomophycece, 

 but in his former treatise used that of Diatomacece, "die 

 Siisswasser Diatomaceen ;" and in this he has been followed 

 by Grunow, Heiberg, Schuman, Cleve, and Suringar. Dr. 

 Pfitzer, however, maintains that the name Bacillariaceoi 

 should be substituted, the genus Bacillaria having been 

 established by Gmelin in 1788, whereas the genus Diatoma 

 was established by De CandoUe in 1805 ; and some of the 

 older writers on the subject have used this designation. It 

 may be deemed inconvenient now to abandon the name of 

 the group which has been so generally adopted by recent 

 writers, but, on technical grounds. Dr. Pfitzer's view is un- 

 doubtedly correct. 



The most interesting portion of the introduction is, perhaps, 

 that in which the author sketches the gradual progress of 

 knoAvledge regarding the true structure and develoj)ment of 

 the diatomaceous frustule, from its first dawn to the present 

 moment. The bivalve chciracter of the frustule was known 

 before adequate notice had been taken of the hoop, or con- 

 nective membrane, which binds the tAvo valves of the frustule 

 together. An even after the importance of this part of the 



' A critical review of this book will be fouud iu ' Journ. Bot.,' ISGi, pp. 

 321-323. 



