STRUCTURE OF THE CELL CONTENTS. 



43 



o 



in the unstained preparation, on account of their high refractive 

 power. They the bodies, not their enveloping framework were 

 first observed by Y. BABES (I.), then studied by P. ERNST (I. 

 and II.), and were regarded as the starting-point of spore forma- 

 tion, being on that account designated sporogenic granules ; but 

 this assumption has, with good reason, been contested by later 

 workers. For a more accurate examination we are indebted to 

 SCHEWIAKOFF (I.), according to whom each of these small en- 

 closures contained in the honeycomb cells possesses a thin skin, 

 the presence of which can be convinc- 

 ingly demonstrated by pressing the pre- 

 paration under a cover-glass, whereupon 

 the skin bursts, without, however, its 

 contents being dispersed. The latter 

 can therefore only be of a solid and not 

 of a fluid nature. The chemical nature 

 of the skin is unknown ; it does not 

 give the cellulose reaction. So far as 

 the composition of the granular contents 

 is concerned, the last-named investigator 

 has identified therein by micro-chemical 

 means potassium, calcium, and oxalic 

 acid, in addition to the indeterminate 

 organic matter. In their behaviour, more 

 closely investigated by WAHRLICH (I.), 

 towards colouring and solvent reagents, 

 these enclosures in the central body of 

 the bacterium resemble those granular 

 constituents of the cell nucleus of higher 

 plants known as chromatin granules, on 

 account of their high power of absorbing 

 colouring matters. On the other hand, 

 the reticular mass of the central body 

 resembles in point of structure and 

 micro-chemical reaction the lignin of the 

 nuclear framework of the cells of higher 

 plants. 



These observations led BUTSCHLI (II.) 

 to the opinion that the central body of bacteria should be regarded 

 as the (comparatively large) nucleus thereof, whilst, on the other 

 hand, the above-named parietal layer corresponded to the cytoplasm 

 of the cells of higher plants a conception which has not withstood 

 the test of criticism. 



The structure of the parietal layer has not yet been determined 

 with certainty. Sundry observations, however, indicate that it 

 exhibits a radial honeycomb appearance. It is in this layer that 

 the colouring matter of the chromogenic bacteria is lodged, whereas 

 the granules of sulphur in the sulphur bacteria are located in the 



FIG. 9. Chromatium Okenii. 



A. Longitudinal section. 



B. Cross section. 



phur granules by solvents, 

 and finally stained with 

 hfematoxylin. The reticu- 

 lated structure of the 

 (hatched) central body (c), 

 as also of the parietal 

 layer (6), and the dark 

 chromatin granules (s), 

 Biitschli's "red grains," can 

 then be detected. Magn. 

 2000-2500. (After Biitschli.) 



