BEPKODUCTION 425 



In some of the Thattophytes the new wall is formed with- 

 out the intervention of a spindle. After the two new nuclei 

 have taken up their positions, the new wall arises midway 

 between them as a ring-like outgrowth from the original cell 

 membrane, and gradually grows inwards till it is complete. 



In the divisions of the protoplasts which constitute a 

 coenocyte the nuclear divisions are not followed by the 

 construction of any cell-walls, so that the limits of each 

 protoplast are not well denned. 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 differentia- 

 tion among themselves, but are all alike in appearance, 

 structure, 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 con- 

 sist 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 



