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On a Form of Structural Division of the Endoplasm 



OBSERVED IN THE BaCILLI OF THE BUBONIC PlAGUE AND 



OTHER Microbes. 



By a. a. Merlin, F.R.M.S. 

 {Read June 15th, 1900.) 



Probably there are no objects on which in recent years so much 

 labour has been expended, and which have been so persistently 

 and diligently scrutinised under the highest powers of the 

 microscope, as the Bacteria. Under such circumstances as these 

 it may seem rash to suppose that any of the well-known forms 

 should possess resolvable structural features hitherto overlooked 

 and unrecorded. As, however, the microbe cell is usually described 

 as typifying the simplest existing cell structure, in which only a 

 kind of granulation has bt en occasionally seen, it may prove of 

 interest to draw your attention to the fact that certain exceedingly 

 minute internal structural details have been recently observed 

 within the stained forms of the bubonic plague and some other 

 bacilli, pointing to the existence of a regular subdivision, or 

 partition, of their cell contents. 



In the accompanying figures I have endeavoured to delineate 

 the points referred to, which may be observed in any well-stained 

 balsam preparations of the specified forms, only requiring good 

 optical means and careful manipulation to render them visible. 



Figures 1 to 7, inclusive, are sketched from cultivated and 

 strongly blue-stained specimens of the plague bacillus, which 

 species has been found on the whole to show the structure in 

 question more plainly than any yet examined. 



Fig. 1 is of a double form, measuring in its entirety about the 

 y^j-g^th of an inch in longitudinal diameter. The upper compo- 

 nent cell has a distinct central constriction, its darkly stained 

 endoplasm being separated, and divided into four equal portions, 

 by a cross partition apparently composed of the same substance 

 as that of the investing envelope ; in other words the cell contents 

 appear to be symmetrically embedded in, and separated by, the 

 homogeneous gelatinous material of which the remainder of the 

 cell is composed. The lower cell has no central constriction, its 

 contents being arranged as figured. In this, and most other 



JouRN. Q. M. C, Series II.— No. 47. 28 



