INCREASE OF CELLS. 



233 



merely dealing with products resulting from the death of a, 

 not with the actual living a itself. The course which the 

 pabulum takes in the nutrition of the bioplasm of a cell is 

 represented by the arrows in fig. 7, PI. XVI, Part III, 



P- 2 74. 



Of the Increase of Cells. Several distinct modes of cell 

 increase or multiplication have been described, but in all 

 cases the process depends upon the bioplasm only. It is this 

 which divides ; and it is the only part of the cell which is 

 actively concerned in the process of multiplication. It may 

 divide into two or more equal portions, or give off many 

 buds or offsets, each of which grows as a separate body as 

 soon as it is detached. The new centres (nuclei) may also 

 divide and sub-divide, as well as originate anew in already 

 existing bioplasm; but bioplasm destitute of nuclei, and 

 nucleoli may divide, so that these bodies are not essential 

 to the process as many have supposed. 



The formed material of the cell is perfectly passive 

 in the process of increase and multiplication. No tissue 

 can grow or multiply. Even the apparently very active 

 contractile tissue of muscle has no capacity for increase or 

 formation. It is its bioplasm only that grows and forms. 



If soft or diffluent, a portion of the formed material may 

 collect around each of the masses into which well-nourished 

 bioplasm has divided, but the formed material (cell-wall) 

 does not grow in or move in &&& form partitions , as has often 

 been stated. When a septum or partition exists, it results 

 not from " growing in," but it is simply produced by a por- 

 tion of the bioplasm undergoing conversion into formed 

 material of which the partition is composed. (PI. VI, fig. 3, 

 a and b, page 222.) 



