250 ON THE STRUCTURE OF OSCILLATORIiE. 



small portion of stratum will be found almost completely 

 deserted, bare, deprived of its deep glossy colour, which 

 depended upon the presence of crowded masses of filaments, 

 which have forsaken their home and wandered forth under 

 the stimulus of the surrounding liquid element. Strange to 

 say, after about a fortnight the sides of the glass were less 

 crowded, the stratum having regained a little more colour, 

 and one could almost feel inclined to attach some truth to the 

 naive statement of the same observer, that the filaments leave 

 their slieaths to which they return when it is cold, &c. As 

 everything relating to their natural history is of some interest, 

 I will mention another observation I accidentally made. 

 Having emptied a bottle containing a stock of Oscillatoria, 

 and finding the sides of the bottle in several places covered 

 with them, I detached them from the sides, having previously 

 filled the bottle with water ; the next morning I observed, 

 with some surprise, the rising bottom of the bottle covered 

 with a tolerably dense green stratum, but not a trace of any 

 of the detached pieces which I had left could be found ; they 

 must, therefore, have crowded together, forming a little colony 

 of their own, being, as it seems, of a social disposition, and 

 gregarious in their habits. 



The new species of Oscillatoria * which I shall now de- 

 scribe is peculiarly interesting, from its being apparently in a 

 state of transition, not having its cells filled out by chloro- 

 phyll, and thus admitting of a better observation of its in- 

 ternal structure ; it was found forming an extensive, partly 

 frothy, stratum, of a dirty-green colour (drying blue-green or 

 aeruginous), on stagnant water, and on being disturbed it sepa- 

 rated into small threads, having a twisted, curly appearance. 

 The average diameter of filaments is 1-6000" ; diameter of 

 cells about the same ; they are highly refractive, and the 

 most active I have as yet obsei'ved. I have stated they were 

 apparently in a transition state, because, besides those which 

 have their cells not coloured by chlorophyll, and which form 

 the great mass of them, there are others with only a few cells 

 filled out, appearing green ; and again, others with all the 

 cells of the filaments filled up, and in this, what I suppose to 

 be their mature state, they resemble the usual forms the 

 Oscillator ice present, viz., filaments of a green colour, only 

 that in this instance the striae are very indistinctly developed. 

 In those with transparent, uncoloured cells the striae are well 



* Though apparently common, I have not been able to identify it with 

 any of the great number described by Klitzing ; but as it may nevertheless 

 be known, I have refrained for the present from introducing it under a 

 specific name. 



