82 Dr. Wiltshire's Contributions to Structural Botany. 



coloured granules ; these latter, however, varying in number, 

 colour and size according to the age and figure of the plant. 

 Whatever form the plant may assume in advanced periods of 

 growth, in its earliest which I have been able to detect, it ex- 

 ists as a very delicate cylindrical filament (this is quite distinct 

 however from the form before alluded to) divided at interval! 

 by transverse septa, and presenting therefore a cellular struc- 

 ture. These cells I shall denominate primary cells ; in some 

 of the cells a little point or nucleus is seen, the rest of the 

 cell being bright and transparent, whilst the other cells are 

 filled with a thin green-coloured matter. This point or nu- 

 cleus 1 regard as the first stage of the green granular sporular 

 matter, which in the other cells is distinctly seen as having 

 arrived at its second stage. The further development of the 

 plant appears to ensue from self-division of the primary cel- 

 lule, such division taking place both in a longitudinal and 

 transverse direction ; the granular matter being divided with 

 the cells, and the law being that each primary cell shall form 

 four cells, and each of these four cells four granular masses, 

 so that sixteen granular masses are the result. Thus the 

 primary cell becomes divided transversely, and hence two 

 granular masses are formed ; a single row 7 only of granules 

 however running down the length of the frond. In the fur- 

 ther development these secondary cells become divided lon- 

 gitudinally, so that four tertiary cells result from the primary 

 one, in each of which is contained a granular mass w 7 hich se- 

 parates into two portions. From the wall of separation formed 

 in the longitudinal division being stronger and broader than 

 that of the transverse, and from its withstanding more per- 

 fectly the pressure of the internal coloured matter, a trans- 

 parent band or line is observed to run down the frond between 

 the inner surfaces of the tertiary cells. 



Whilst self-division of the cells has been going on, the frond 

 gradually increases in breadth until the tertiary division be- 

 comes complete, at which it ceases, all further growth being 

 terminal, if the plant is to continue to exist in the cylindrical 

 or linear form ; the green matter however undergoes a change 

 to which we shall allude directly. It will be remarked, that 

 in the form we have just alluded to, although we have two 

 rows of cells running down the frond, only one series of pri- 

 mary cellules has been developed, and upon this fact appears 

 to depend the preservation of the cylindrical figure ; if more 

 series than one are developed, their lateral pressure against 

 the walls of the cylinder causes the latter to become extended 

 laterally, and hence ensues the flattened riband shape or strap- 

 like form ; and according to the number of series of primary 



