246 M. Miiller on the Development of the Lycopodiacese. 



accelerating rapidity, and with it that part of the cytoblast also 

 becomes more fluid which in the foregoing stages was becoming 

 softened at the periphery (fig. 15). Now it appears as a mass 

 composed of very small granules in a state of fine division in a 

 mucilaginous fluid. The end of the next stage is, that the whole 

 cytoblast has become dissolved in the said fluid (PI. V. figs. 16, 

 17, and PI. VI. fig. 1). It very seldom happens, however, that 

 the mass becomes so fluid that granular points are no longer per- 

 ceptible in it (PI. VI. fig. 1). 



In the same figure we see, moreover, that the whole mass has 

 become more agglomerated. That is a further stage, and is 

 always met with before the division of the cell-contents into se- 

 veral portions. The whole mass has returned into the condition 

 of cytoblastema*. Thereupon it becomes retracted either on to 

 the walls of the cell, or, as more rarely happens, into the centre. 



The mass is now seen to be collected into four parts (fig. 2). 

 Thereby either the whole substance is appropriated, or the four 

 portions are formed inside the mass. This is easily explicable. 

 Each of the portions is a cytoblast : it increases in size in the 

 latter case, because that portion of the mass which has not been 

 appropriated in the formation of cytoblasts becomes deposited 

 upon its external surface (PI. VI. figs. 3 — 6). 



- The substance of the cytoblast is still visibly very mucilagi- 

 nous. In the interior of it is seen the central nucleus as a sim- 

 ple granule [Kern). Around it the mass of cytoblastema is so 

 deposited that its outer contour is composed of granules lying 

 heaped together, i. e. very closely applied upon one another 

 (fig. 6). 



In a more advanced stage the cytoblast exhibits an enveloping 

 membrane (Haut) which is as yet very delicate and mucilaginous 

 (fig. 8). It is now manifestly undergoing extension, and the 

 cell-membranes approach toward each other with increasing pace 

 for the tetrahedral junctionf (figs. 6 — 11). 



In fig. 8 a, by c, we find also how the membrane is formed 

 and extends from the cytoblast on one side only, therefore in 

 the same manner which Schleiden first described. Subsequently 

 however the membrane is detached and expands all round the 

 cytoblast (figs. 9 — 10 b). Frequently it becomes detached at 

 an earlier period, as in figs. 11 and 12. 



* Cytoblastema and protoplasma (inch mucilage, Schleim) are essentially 

 one and the same ; yet both names may be used, the latter for the oleagi- 

 nously fluid, mucilaginous mass, the former for the granular and coagu- 

 lated. 



f This is well-known as an expression proposed by H. von Mohl for that 

 position of the secondary cells where their faces, directed toward the centre 

 of the mother-cell, become pyramidally pointed through their reverse super- 

 position, while the outer faces remain spherical. 



