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LIX. Notice of New Discoveries of Ehrenberg* s respecting the 

 Bacillaria?.* By M. Wiegmann. 



'HE readers of this Journal will have seen from Meyen's 

 Report on Botany, (Phil. Mag., present volume, p. 385— 

 390.) that the microscopical animal forms of this family continue 

 yet to be a subject of dispute, inasmuch as they are referred by 

 several botanists to the vegetable kingdom. Meyen is also of 

 this opinion, which seemed to be supported by the circum- 

 stance that these creatures had hitherto not been observed to 

 take in any coloured nutritive substance, like the other Infu- 

 soria. Recently, however, Ehrenberg has succeeded in feed- 

 ing various species belonging to the genera Navicular Gom- 

 pho?iema 9 Arthrodcsmus (Scenodesmus Meyen), Closterium ace- 

 rosum, on which subject he read a paper, at the same time ex- 

 hibiting specimens in proof of this, before the Society of Na- 

 turforschende Freunde at Berlin. Vesicular ventral sacs, per- 

 fectly similar to those of the other polygastrical Infusoria, were 

 apparent. " I could count," says Wiegmann, " with the 

 greatest distinctness from six to seven ventral sacs completely 

 filled with blue colouring matter, in the clear middle part of 

 a Navicula gracilis exhibited by Ehrenberg." With this dis- 

 covery, therefore, the most perfect proof has been afforded of 

 their coincidence with the Polygastrica, which, however, the 

 peculiar gliding motion f which was perceptible in many of 

 them had before sufficiently indicated ; which motion may 

 be plainly recognised in many of them, and cannot be com- 

 pared either with the lively motions of the sporules of Alga?, 

 or with the motions of the Oscillatoria. The foot-like papilla? 

 which these animalcules protrude out of various apertures, and 

 drawback, may also be remarked in many of them: for in- 

 stance, in Navicida very easily, when the water is rather thick ; 

 we can also perceive with the greatest facility the above-men- 

 tioned apertures in the empty shields J of the fossil Infusoria. 



* From Wiegmann's Jrchiv, 1837, part iv., p. 377- Translated by 

 Mr. W. Francis. 



f [I have also lately noticed, in a few species belonging to this family, 

 the peculiar papillae by which they creep along. I may here state that I 

 have often seen various species of Bacillaria and Navicula not only push 

 one another out of the field, but have remarked that they make room for 

 each other, which certainly cannot be attributed to electricity, as Morren 

 supposes, (Phil. Ma^„ p. 389.)— W. F.] 



\ See Ehrenberg s paper in the Scientific Memoirs, vol. i. p. 405. 



