MICROSCOPIC ALG^ AND FUNGI. 205 



ditions, .and consequent want of colour, and are only distin- 

 guished fi'om them by the unessential circumstance of their 

 living in water. But a close investigation of the qenera 

 included under the above term, will show, beyond any doubt, 

 that nearly all the forms of water-fungi are so closely allied 

 to algan genera, that, with the exception of their wanting 

 colour, scarcely even a generic distinction can be drawn 

 between them, and much less one of family. 



Thus the only difference between Hygrocrocis, a so-termed 

 water-fungus, and Leptothrix, consists in the circumstance 

 that the immotile filaments of the latter contain jihi/cochrom^ 

 whilst in the other the contents are colourless. But whilst 

 Leptothrix is, perhaps, inseparable from some forms of 

 Oscillaria, notwithstanding the motility of the latter, so in 

 the same way do the colourless immotile filaments of the 

 genus Beggiatoa come under the class of water-fungi, close to 

 the various forms of Hygrocrocis. It has already been 

 remarked by Nageli that the yeast-fungus corresponds in 

 form and mode of germination with the algan genus Exococcus.^ 

 Sarcina is morphologically identical with Chroococcus, and 

 that, in its vegetative and reproductive condition, Achhja 

 corresponds with Valonia or Bryopsis. 



With respect to the genus Stereonema, Kutz., Dr. Cohn 

 proceeds to show that the filamentous growth so named, is 

 not an Alga or Fungus at all, nor in fact any kind of inde- 

 pendent organism, but that they are the stems of an infusorium 

 — the Anthophysa AluUeri, Bory. 



The bunches of apparent spores at the extremities of these 

 filaments are regarded by Dr. Cohn, tliough apparently not 

 without hesitation, as identical with the Uvella uva of Ehren- 

 berg ; and, consequently, they are in his view to be looked 

 upon as belonging to the animal kingdom, for he seems, like 

 many other German observers, still to adhere to the exclusively 

 animal nature of many of the Ehrenbergian Monadina. 



The loss thus inflicted upon the vegetable kingdom by Dr. 

 Cohn, is, however, compensated by the addition to it of part 

 at least of the Vihrionia. The animal nature of these minute 

 creatures has, hitherto, never been disputed ; but Dr. Cohn 

 sees reason, and affords what appear to be good grounds for 

 it, to believe that several forms of the Vibrionia may be 

 certainly shown to belong to the vegetable khigdom. 



The form which seems to have constituted the principal 

 subject of Di\ Cohn's researches in this respect, is that known 

 as Vibrio lineola, Ehr., but which was separated from the other 

 Vibriones by Dujardin, under the name of Bacterium termo. 



The result of his investigations is, that the corpuscles uf 



