CELL-DIVISION 23 



the cell-wall into mucilage at this part. The final stage (/) consists 

 of a rounding off of the ends of the daughter-cells at the point of 

 junction, after which they gradually draw apart, the substance con- 

 necting them is dissolved, and henceforth the two halves lead a separate 

 existence. Each grows to maturity, and the process of division is 

 repeated. In the other way, the process of cell-division is completed 

 as shown in d', e', in which the thin clear line appears very soon after 

 the beginning of the constriction {d'). The subsequent development is 



e 



Fig. 36. — Cell-division in rod-cells. (For explanation sec text.) 



the same, viz. a rounding off and separation of the cells (e'). Whilst 

 this latter process is going on the new cell-wall that has been formed 

 at the line of separation of the two daughter-cells thickens, until the 

 wall of the new cell is uniform throughout (/ and e'). In some cases 

 the mucilaginous substance which binds the two daughter-cells does not 

 immediately dissolve, so that one sometimes sees two newly formed 

 daughter-cells separated by a distance equal to their own length, but 

 evidently still connected by an invisible thread of mucilage, which 

 can, however, be made visible by appropriate staining.^ 



2. Cell-division in the Coccaceae. In healthy cultures the pre- 

 dominant forms are one one-, two-, three-, and four-celled individuals, 

 which, unlike the bacillus group, usually divide before expansion takes 



' Cell-division in the genus Paeudomonas has not yet been investigated. There 

 is very little doubt, however, that in all essentials, this process agrees with that 

 observed in the genus Bacillus. 



