416 VEGETABLE PHYSIOLOGY 
In some of the Thallophytes the new wall is formed 
without the intervention of a spindle. After the two new 
nuclei have taken up their positions, the new wall arises mid- 
way between them as a ring-like outgrowth from the original 
cellmembrane, and gradually grows inwards till it is complete. 
In the divisions of the protoplasts which constitute a 
ceenocyte the nuclear divisions are not followed by the 
construction of any cell-walls, so that the limits of each 
protoplast are not well defined ; in some cases indeed they 
are indistinguishable. — 
The reproduction of the protoplast is sometimes attended 
by the production of not two but several, which appear 
simultaneously. Such a case is illustrated by the forma- 
tion of the endosperm in the embryo sac of the Phanero- 
gams. It is, however, only a modification of the process 
already described. The division of the original nucleus is 
followed by the disappearance of the spindle ; the daughter 
nuclei divide in turn, and the process is continued until a 
large number of free nuclei lie embedded in the protoplasm 
of the cell. These then become connected with each other 
by the simultaneous development of connecting fibrils or 
small spindles like the first, and cell plates, which later 
become cell membranes, arise across them as in the case 
described. The protoplasts so formed exhibit no differen- 
tiation among themselves, but are all alike in appearance, 
structuré, and fate. 
This modification of the process of reproduction of the 
protoplast is known as free cell formation, and in many 
cases it is attended by a specialisation of function, which 
will be alluded to a little later. 
In many cases of the reproduction of such plants as 
consist of enormous numbers of protoplasts variously 
arranged and differentiated, we have to recognise essentially 
no other process than the multiplication of the protoplasts 
by such means as we have just described. Generally in 
these cases some. part of the parent plant becomes detached 
and grows at once into the new individual. We have seen 
