INTEODUCTION TO IRON-BACTEBIA 



159 



sometimes as much as 12-16 yu and even 20 /i. Multiplication takes 

 place as in Crenothrix polyspora by the splitting up of the cells into 

 a number of small motionless bodies, each of which is capable of 

 developing into a new organism. 



Spirophyllum ferrugineum (Ellis). This member of the group was 

 first observed near Glasgow, but though very seldom present in large 

 quantities, is widely distri- 

 buted in Great Britain, being 

 found as far south as Kent 



dn ,1 , FlQ. 102. — Spirophyllum ferrugineum. 



as far north as the f f ^ b f 



Orkneys. Each individual takes the form of an elongated, flattened 

 and spirally-twisted cell, a typical example being represented by 

 Fig. 102. There may be only a quarter of a turn, or there may be 

 fifteen or more. The width various, from 1 /j, to 

 6 /i, whilst the length may reach anything up to 

 200 fi and possibly more. There is no definite 

 cell-membrane, protection being afforded by the 

 great thickness of the cells at the edges. This 

 is shown diagrammatically in Fig. 103a. This is 

 probably a great help in protecting the cell from 

 tearing when it twists itself spirally, especially 

 in view of the fact that the twisting continues 

 after a fairly large amount of iron has been de- 

 posited on the cell. The ends of the cells are 

 usually angular and irregular. The spirals may be close or wide 

 apart. 



Conidia formation, which takes place in precisely the same manner 

 as in Leptothrix ochracea, is the usual method of multiplication. 

 Large numbers are formed, and when, as often happens, these remain 

 attached to the parent plant, the latter is completely hidden, so great 

 is the mass of these bodies. Each conidium has a single coat, and 

 measures 1 /u. in width and 1"75 /j. in length. In germination the coat 





Pig. 103.— Spirophyllum 

 ferrugineum. (a) Cross- 

 section, showing thickened 

 margin ; (6) germination 

 of conidium ; a;=eonidium- 

 coat. 



Fig. 104. — Spirophyllum ferrugineum. Two intertwining individuals. 



bursts, allowing the contents to protrude (Fig. 1035). Very soon 

 after germination the young cell assumes a flat irregular shape, begins 

 to twist, and also to exhibit an independent movement, partly of 

 a wriggling and partly of a pendulum nature. At a slightly later 



