THE INTIMATE STRUCTURE OF THE CELL 185 



AcHROMATiUM MOBILE (Lauterbom), syn. Microspira 

 VACiLLANS (Gicklhorn) (see Fig. 16). 



The general appearance of the organism is described on 

 page 121. The cell is limited by a distinct membrane, which 

 can be separated by plasmolysis, and is almost completely 

 filled by two or a very small number of large globules. In 

 addition, there are five to fifteen smaller globules. Gicklhorn 

 considers the smaller to be composed of sulphur, but is uncertain 

 of the constitution of the large bodies. Each of these appears 

 to be formed by secretion into a previously formed vacuole, 

 which is limited by a wall. The formation of a vacuolar 

 wall is unknown in plant cells, and the observation needs 

 confirmation. 



The plasma is stated to be confined to the periphery of 

 the cell, but there must be bands of plasma running across, 

 otherwise it would be difficult to account for the vacuoles ; 

 there must be a plasma to form a matrix in which the vacuoles 

 can form, for each must be sufficiently large to admit of the 

 formation inside it of one of the " large bodies." The cell 

 does not contain a well-defined nucleus. 



Thiovulum Mulleri (Warming), Lauterborn. 



This peculiar organism was investigated by Hinze (6) from 

 material obtained from the Gulf of Naples (see Chap. VIL), 

 and differs essentially from any of the organisms hitherto 

 considered, by exhibiting longitudinal cell division. The cell 

 is bounded by a delicate membrane, and the plasma consists 

 of delicate strands which, however, are completely absent 

 from the centre of the cell, which is occupied by a large oval 

 vacuole. At the thicker end of the cell is an aggregation of 

 plasma in which numerous sulphur globules are placed (Figs. 

 18-19). 



In addition to sulphur, Hinze found large grey-green struc- 

 tures of fugitive existence which he regarded as a form of 

 reserve material (Fig. 18). Further, he found in the plasma 

 very fine granules which colour in the same way as the nucleus, 

 and which also he regarded as reserve food. 



