REPRODUCTION IN PLANTS 93 



Moreover, this spore now begins a series of cell divisions 

 which result in a new filament, or individual. It will be noted 

 that the potentialities of the spore and the protoplasts which 

 continue to retain their stations in the parent body are in- 

 trinsically the same, but the opportunity of the spore is dif- 

 ferent. In brief, the fact that the spore has separated from 

 the parent stock appears to be the reason why it reproduces. 

 Therefore a SPORE may be defined as a cell, or the essential 

 part of a cell, the protoplast, which has separated from one 

 plant body and is capable of producing another plant body. 

 This statement might, at first glance, seem to indicate that 

 spore formation is restricted to plants with multicellular 

 bodies, whereas we have seen that spore formation occurs 

 in the life cycle of Sphaerella. This apparent contradiction is 

 cleared away when we recall that in the latter the cell divi- 

 sions which produce the spores do not involve the cell wall; 

 merely the protoplast within divides and the daughter cells 

 make their escape. (Fig. 9.) 



Therefore spore formation is not a necessary result of the 

 establishment of a multicellular body, but an inheritance 

 from unicellular forms which makes possible one of the two 

 effective types of asexual reproduction in the Metaphyta. 

 The other type is FRAGMENTATION, which consists essentially 

 in the separation from the body of larger or smaller parts, 

 which later reproduce the whole plant. It is a familiar fact 

 that, under proper conditions, cuttings, buds, bulbs, and 

 sometimes pieces of leaves may reproduce or, as it is some- 

 times stated, REGENERATE a complete plant. This is just an 

 expression of the same power which the spore, though a single 

 cell, exhibits. It regenerates, as it were, a plant body similar 

 to the one from which it has separated. 



