RECENT RESEARCHES INTO THE HISTORY OF BACTERIA. 271 



take on the appearance of zooglsea ; and while Professor Lan- 

 kester went a long way towards convincing him that Spirillum 

 undula formed zoogloea masses (cf. 'Quar. Jour. Micro. Sci.,' 

 xiii, Plate XXII, figs. Sand 9), Cohn himself saw a colourless 

 Leptothrix-like fibre in a"glia^'; but as he never observed 

 genetic connection between this form and Spirillum, he 

 thinks it better to call it Myconostoc n. g., as it is among the 

 Bacteria, a form parallel to Nostoc among the Algae, and to 

 give it the specific name of gregarium, because of its social 

 character. 



20. Another new genus ( Cladothrix dichoiomd), which Cohn 

 has lately observed, gave him, at first, a great deal of trouble ; 

 he found colourless fibres very finely granulated, and ap- 

 parently unsegmented^ which resembled Leptothrix, save 

 in this that they appeared to branch with great regularity ; 

 this was difficult to believe, because neither Leptothrix nor 

 Oscillaria ever present such branchings ; but examined with 

 a higher power, these organisms were seen not to present a 

 true dichotomy, but that false branching which is so charac- 

 teristic of the Scytonemece allied to the Oscillarige, which 

 is brought about by the apposition of two fibres, which, 

 while growing divergently at their upper, grow in apposition 

 at their lower ends. 



This mode of origin of false branches agrees so closely 

 with that observed in Schizosiphon and other OscillaricB, that 

 Cohn congratulates himself on the discovery, as tending to 

 confirm his views of the close relationship which these putre- 

 factive forms have to the Oscillariae. 



21. The next Bacterium described is also a new species, 

 although the genus Streptothrix — the new form has the spe- 

 cific name Foersteri — is well known; the place in which this 

 form was found was the lachrymal canal, where such organisms 

 were first observed, in 1855, by the famous von Graefe, since 

 which time other observers have also noticed them. Professor 

 Foerster coming across it sent specimens to Cohn, who ree 

 cognised specific differences between this form and th- 

 L. buccalis which is found in the mouth, inasmuch as this 

 latter is thicker, straight, while L. Foersteri is screw-shaped, 

 like Spirochete. L. buccalis is never branched as the new 

 form frequently is. The full account of this form and the 

 elaborate comparison which he sets forth between it and 

 L. buccalis will have much interest for those who busy 

 themselves with these remarkable parasites. 



22. It would be strange, indeed, if any writer on Bacteria 

 in the sad times in which our lot is cast, should not have his 

 say about the question of spontaneous generation, flooded 



