33 8 BOTANICAL GAZETTE [October 



Vegetative multiplication 



In one-celled plants the individual and the cell are identical. 

 Among the varied activities of the protoplast, the power of self- 

 division is one, and in such plants this division results in two new 

 individuals. In other words, this is reproduction, and the con- 

 clusion is that the fundamental mechanism of reproduction is cell- 

 division. There is nothing more in the machinery of reproduction 

 than this phenomenon of cell-division, whether it be sexual or asexual 

 reproduction. If the essential machinery of reproduction is pro- 

 vided for in cell-division, it follows that the cell-fusion connected 

 with the sex act must be regarded as an addition to the funda- 

 mental process of reproduction, an added preliminary process, not 

 necessary to reproduction, but securing something in connection 

 with it. In fact, the extent to which asexual reproduction occurs 

 among plants is not fully appreciated. It is probably true, taking 

 the plant kingdom as a whole, that the multiplication of individuals 

 is greater by asexual than by sexual methods. The abundant 

 asexual reproduction even among angiosperms testifies to the fact 

 that asexual reproduction is not even a declining method. What 

 may be called the first stage in the evolution of asexual repro- 

 duction, therefore, is represented by those one-celled plants whose 

 only method is ordinary cell-division, which is a function exercised 

 by any protoplast under appropriate conditions. 



Reproduction by spores 



Among many-celled plants, ordinary cell-division usually does 

 not result in new individuals, but in the growth of the individual. 

 This transition from cell-division resulting in new individuals to 

 cell-division resulting in growth is associated with the establish- 

 So long as proto 



ment 



plasts are held together by their walls in the continuous framework 

 of an individual, there can be no production of new individuals. 

 There must be detachment from the parent stock as a preliminary 

 to the series of cell-divisions that are to result in the new indi- 

 vidual. Among the lower algae this is accomplished in a very 

 simple way. The protoplast detaches itself from the cell wall and 



