HARDWICKE'S SCIENCE-GOSSIP. 



25 



HISTOEY OF THE DIATOMACE.E, 



{Continued.) 



N the year 1S27 

 C. A. Agardh dis- 

 covered several 

 new diatoms, 

 wliicli he descri- 

 bed in the Regeus- 

 burg Botanical 

 Journal, and men- 

 tions for the first 

 time the genera ^licromecja, 

 Licmophom, and Homaocladia. 

 The same algologist wrote 

 more particularly of this family 

 in four theses, which appeared 

 with the title "Conspectus 

 Criticus Diatomacearum ;" in 

 the first and second he descri- 

 bed a great number of forms, 

 partly already known and 

 partly new, under the genera 

 Cymhella, ScJtizonema, 3Hcro- 

 mega, Berkeleya (this genus was constituted by 

 Greville in 1S27), Homceocladia, Gloeodidyon, Hy- 

 drurus, and Gloenema. In the third part (1S31) he 

 gave the genera Gomplionema, Styllaria {=Podo- 

 sphenia, Ehr.), Meridian, Licmophora, and Frustulia ; 

 in the last part (1832) Isthmia, Odontella, Desmi- 

 dium, Achiantlies, Striatella, Fragilaria, Grammo- 

 nema (belonging to the Desmidiece), and Melosira. 

 (Kiitzing was wrong in referring Grammonema to 

 Desmidieae. This form is probably an imperfectly 

 siliceous Eragilaria, and it is, moreover, a marine 

 species. — F.K.) lu the whole the author describes 

 about 116 species of Diatomacea?. Greville had 

 already described (1827), in the " Scottish Crypto- 

 gamia Elora," vol. v., the genera Exilaria, Monema, 

 and Berkeleya. 



In 1S2S Turpin founded the genus Surirella, and 

 Gray, in 1830, the genus Biddulphia, from Conferva 

 Biddulphiana and C. obliqtiata of the Eng. Bot. 

 No. 110. 



Thus, till the year 1S32, stood the systematic 

 labours on these microscopic organisms, most of 

 the writers mentioned considering them partly as 

 animals (the moving forms) and partly as plants 

 (the fixed forms). Agardh, Lyngbye, and Leiblein 

 advocated decidedly their vegetable nature; but, 

 beside Schrank, there was none who decidedly ad- 

 vocated their animal character ; of their life-history 

 nothing was known beyond the thorough communi- 

 cations of Kitzsch, and the more' superficial obser- 

 vations of Gaillon, that might have brought the 

 question as to their nature nearer solution. 



In the same year (1832) appeared the second- 

 " Contributions to the Knowledge of the Minutest, 

 Organisms," by C. G. Ehrenberg. In this the 

 Diatomacese were considered as decided animal 

 forms, and were included with the infusoria under, 

 the family of "staff auimals" (Stiibthierchen, in- 

 cluding Desmidieae); in the class of "stomach- 

 animals." (Magenthiere). But, at that time, sto- 

 machs were as little recognized by the author as- 

 mouth, entrails, or rectum ; but a bivalve shell and 

 a changeable foot (verjinderliche Sohle) (like the 

 Gasteropods) and said to stretch out the longitudinal 

 cleft of both valves, was mentioned. Another com- 

 munication from the same author followed in 1834, 

 in which were described sixteen newly observed 

 forms. The descriptions communicated in these 

 observations are of the greatest importance, and 

 are given with a care hitherto unknown in this 

 field. The author had this advantage over his pre- 

 decessors, that in his investigations he could make 

 use of the best microscopes. (The best microscopes 

 of this period probably did not equal in performance 

 such as may now be obtained for four or five pounds. 

 In 1831 Messrs. Goring and Pritchard published 

 the " Micrographia," in which is a dialogue be- 

 tween Tobias Oldbuck, Esq., naturalist, and Mr. 

 William Putty, optician, on the comparative merits 

 of the old-fashioned simple microscope and the 



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