102 VEGETABLE CELLS. 



cell-formation, the first process is the formation of one or 

 more heaps of mucilage-granules, according as one or 

 more cells are to be produced. At first these heaps have 

 no definite boundary, but pass insensibly into the remain- 

 ing mucilaginous contents of the cell. Subsequently the 

 outline becomes more sharply defined, they are surrounded 

 by ray-like circulation-filaments (fig. 1). The outline 

 becomes still sharper, and then but a few filaments 

 remain (fig. 2). At length the surface of the heaps of 

 granules becomes smooth, and now an inclosing mem- 

 brane gradually makes its appearance (fig. 3). Has this 

 membrane originated on the periphery of the granular 

 accumulation, or has it been formed in its interior as a 

 minute cell, and in growth gradually absorbed its contents 

 from without? I am compelled to regard the former 

 view as correct, because nothing can be seen of the latter 

 process, even in very transparent heaps of granules. That 

 the membrane originates on the surface of the subse- 

 quently inclosed contents is in the highest degree pro- 

 bable, from the analogy with the parietal cell-formation in 

 the same plant ; for while a free sporangium is forming in 

 the interior of one clavate branch, in others the whole 

 clavate extremity becomes a sporangium (fig. 7). Here 

 the cell is not formed in the interior as a little free cell, 

 but its walls originate in the very place where they first 

 become visible. Now the two facts support each other, 

 and in such a way that, taken together, they prove the 

 origin of the membrane on the surface of the contents. 

 That in the apparent formation of a mere septum, a perfect 

 cell actually originates,, lying in contact with the wall of 

 the branch (not a mere wall), is shown by the analogy with 

 the second case, where a perfect sporangia! cell is formed 

 at some distance from the wall of the branch. That in 

 free cell-formation the membrane originates on the surface 

 of the contents (not in the interior of them, around a 

 nucleus, or in any other way), is shown by the analogy 

 with the first case, where the cell-membrane is formed in 

 like manner on the periphery of the contents. The dis- 



