igo SULPHUR BACTERIA 



plasma, in which case it is not necessary to postulate the 

 existence of connecting plasma threads. The inner proto- 

 plast is about 4ju- in thickness, whilst the centre is occupied 

 by a large vacuole. The inner protoplast is not reticulated, 

 and frequently contains a large number of small round globules 

 of calcium carbonate (see Fig. 30 a and b). When the organism 

 is slowly rotating it can be seen that these bodies are confined 

 entirely to the inner protoplast. As already stated, Gicklhorn 

 suggests that this is an example of a new class of organisms 

 which he proposes to name lime bacteria. All the round globules 

 are not composed of lime, for whilst some (the lime globules) 

 do not stain with methylene blue, others do take up the stain. 

 The globules that take up the colour arc probably reserve 

 material. This is supported by the fact that their number 

 fluctuates, suggesting that they are first stored, and then used 

 up during metabolic processes. 



There are also very small granules distributed in the 

 cytoplasm but their nature is unknown. 



The sulphur globules are distributed in the plasma and when 

 present their number varies considerably. 



The colouring matter is pinkish-purple in tint and diffused 

 uniformly throughout the plasma, a detailed account of the 

 pigment is given in Chap. XIII, 



Summary and Conclusions. 



The intimate structure of the cell in the sulphur bacteria 

 shows the same primitiveness as the rest of the Schizophyta. 

 There is less differentiation than is found in the cells of the 

 higher Fungi, or of the Algas. With one exception [Beggiatoa 

 mirabilis), the outer envelope or "membrane" is plasmatic, 

 and distinguished from the inner plasma only by its greater 

 density. It takes up the same stains, and in the one species 

 tested, namely, Chromaiium Linsbaueri, is the base to which 

 the cilia are attached. 



Division throughout the group is by the simple fission 

 characteristic of the Schizophyta. The cells when divided 

 maintain connection for a period by a bridge of slime, but 



