1881.] 



MICROSCOPICAL JOURNAL 



53 



vide into tetrahedra, so that mulberry- 

 like cell-colonies are produced. The 

 general envelope becomes liquefied, 

 so that only thin circular borders can 

 be seen. The size of the single, finally 

 spherical cells, was different ; I mea- 

 sured diameters of 3 — 7/^. Division 

 occurred in cells of every size. 



Finally, the formation of these te- 

 trahedra also ceased ; from them the 

 enveloped Gloeocystis form was pro- 

 duced. Single, special vesicles, how- 

 ever, produced the spherical cells in 

 cylindrical envelopes, which increased 

 in size, escaped, and reproduced the 

 form from which I started. In this 

 generation I observed the already 

 mentioned division into four parallel 

 cylindrical daughter cells, placed in 

 the direction of the axis. Cells which 

 did not divide, swelled greatly, up to 

 10 in diameter, and bore on the sur- 

 face of the walls a short, conical pro- 

 jection. A process of copulation, 

 which I expected to observe here, did 

 not take place. The chlorophyll- 

 contents of these cells, had accumu- 

 lated in an elongated ball upon that 

 part of the cell-wall opposite to the 

 projection, the plasma occupying the 

 rest of the cell was turbid and granu- 

 lar. Finally the entire contents es- 

 caped by the solution of the enclosing 

 membrane. The chlorophyll balls did 

 not break up, but I observed them 

 half a day or more and detected a 

 fine membrane around them. They 

 were not followed any further. 



In GlcBocystis rupestris. Rab., which 

 I have frequently found this Summer 

 on rocks in moist forest ground near 

 Dresden, I have likewise observed 

 that free, or naked, cylindrical cells 

 belong in the form-circle ; these are, 

 as already remarked, Falmoglcea lu- 

 rida and rupestris, Ktz. It is to be 

 hoped that the form-changes of 

 Gl. fenestralis, Al. Brann, may also 

 be made out. 



According to my observations, it 

 appears that in Gloeocystis there is a 

 form-series of cylindrical cells, which 

 may be either enveloped or free, 

 which alternate with the common 



spherical and enclosed cells, and 

 that within this latter series there is 

 a Paltnella condition with tetra-divi- 

 sion. 



Likewise the Falmoglcea species, 

 in which no copulation was observed, 

 and which, therefore, fits in no par- 

 ticular place, has found its position ; 

 for it may be assumed that for those 

 not here mentioned, in case they are 

 not identical with those placed in the 

 form-circle of Gl(Kocystis, similar re- 

 lations will be found. 



I remark still, that I have not only 

 derived the Gloeocystis form from the 

 Cylindrocystis form, but I have also 

 collected, especially in forest-ground 

 and on masonry, the Palmella condi- 

 tion and the true Gloeocystis form, 

 from which I saw the Cylindrocystis 

 form develop. It now remains to es- 

 tablish the synonyms for Gloeocystis, 

 which I suppose to be Gloeocapsa, 

 Cylindrocystis and Microcystis. 



After long rains, one will have 

 good opportunity to collect the Pal- 

 mella condition, in mountainous 

 places, and to control my observa- 

 tions. 



Leipzig- Anger, October, 1880. 



Photographing Bacteria. 



In the Zeitschrift fur Mikroskopie 

 there is a short article on this subject 

 by Mr. K. L. Kaschka, which will 

 doubtless be of interest to some of 

 our readers. The excellent photo- 

 graphs by Herr Koch, at first led the 

 author to believe that they could be 

 made without great difficulty, but an 

 unexpected difficulty was soon met 

 with, namely, it was impossible to find 

 a coloring matter which would so act 

 upon the sensitive plate as to make 

 the bacteria print sufficiently black. 

 Anilin colors, methyl violet, fuchsin, 

 and brown, were first tried, but only 

 the first two colored the bacteria well, 

 and although deeply colored as viewed 

 by the ocular, they were scarcely to 

 be distinguished on the photographic 

 plate, even when the latter was made 

 very sensitive. Tincture of iodine 



