38 VARIATIONS IN MORPHOLOGY [CH. iv 



which emerge after sundown and the next day split up into 

 innumerable little bacteria rods (Kerner and Oliver). 



The zoogleae in which bacteria are massed together are to 

 be regarded as a resting stage in their life history. The swollen 

 envelope or matrix in which they are embedded, and which 

 in some cases becomes hard and chitinous, being protective in 

 character. 



It is important however to recognise the fact that these 

 zoogleae are merely conglomerations of a number of organisms 

 and are not, strictly speaking, individuals themselves. Too 

 great stress must not be laid, therefore, on their formation 

 and the changes they undergo as evidence of variation on the 

 part of the individuals composing them. 



A regiment of soldiers during manoeuvres is composed of 

 a number of individuals, all of the same kind, comparable to 

 pathogenic bacteria. It assumes various forms from time to 

 time that of serried ranks when marching, a filamentous form 

 when advancing in single file, a "square" when awaiting a 

 cavalry charge and yet another appearance during its resting 

 stage when bivouacked for the night. Again, a mass meeting 

 or "demonstration" of coal miners, composed of a different 

 type of individual all again of the same kind, comparable 

 to a harmless pigment-producing organism shows quite a 

 different formation, namely that of an irregularly shaped crowd, 

 the units of which are arranged somewhat concentrically. 

 There is sometimes a tendency to the formation, at the peri- 

 phery, of smaller collections or nodules showing a similar 

 concentric arrangement. There is a constant tendency on the 

 part of a regiment or a miners' "demonstration," wherever we 

 find them, to reproduce exactly the forms described as typical 

 of each. A regiment of soldiers or a crowd of pitmen may be 

 regarded as a separate entity in one sense, but neither is an 

 individual in the sense that a tree, composed of vegetable cells, 

 is one. There is no interdependence of one part upon another 

 in a body of troops or a crowd. They are temporary and can 

 be dispersed, the individual units surviving though separated 

 from each other. Moreover the forms they assume are not 

 invariable. A regiment of soldiers, if a certain controlling 



