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 



FIG. 36. Cell-division in rod-cells. (For explanation see 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. 1 



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 



1 Cell-division in the genus Pseuclomonas 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. 



