CONTRIBUTIOXS TO THE CYTOLOGY OF THK BACTERIA. 401 



Babes (1889) found stainable granules — whose presence he 

 had recorded at an earlier date — in various bacterial cells. 

 Later (Babes, 1895), he named them "metachromatic granules," 

 but he was unable to determine their precise significance. 



Ernst (1888) found similar granules in the cells of Bacillus 

 xerosis. They were observed in dry, flame-fixed cells, 

 stained with methylene blue and Bismarck brown. He 

 believed that they took part in spore-formation. Subsequently 

 (Ei'ust, 1889) he found similar granules — using similar methods 

 — in a number of other Bacteria. He proposed the name 

 '' sporogenic granules" for them, and regarded them as 

 probably of a nuclear nature. Still later (Ernst, 1902), he 

 described "chromatophil" graimles — of uncertain significance 

 —in many Bacteria ( B. megatherium, water Bacteria, etc.). 

 These granules were coloured by intra-vitam staining with 

 methylene blue and neutral red. 



The carefully conducted and classic work of Biitschli (1890, 

 1892, 1896, 1902) can here be considered in its main outlines 

 only. After studying the Cyanophyceas, Biitschli turned his 

 attention to the large sulphur Bacteria.^ In these he believes 

 that the protoplasm, which has an alveolar or honeycomb 

 sti'ucture, is ditt'erentiated into a ])eriphei'al layer and a denser 

 " central body." In the meshes of the latter, granules which 

 stain red with hfematoxylin (" red granules ") are present. 

 He regards the "central body" with its "' red grannies " as 

 the homologue of the nucleus of other cells, and the peripheral 

 layer as the homologue of the cytoplasm. In the smaller 

 Bacteria which he investigated, he found that the peripheral 

 layer was relatively greatly reduced in size, or altogether 

 absent — the greater part, or the whole of the cell being there- 

 fore constituted by the "central body." He was therefore 

 led to regard the whole cell as homologous with a nucleus. 

 The observations were made not only upon living- cells, but 

 also upon cells fixed, stained and variously treated by a 

 number of different reagents. 



1 The earlier work of Winogradsky (1888) and others, upon this 

 gronp, did little to elucidate the structure of the cells. 



