NATURE AND RELATIONS OF REPRODUCTION 325 



species of Aira, and Festuca, and Saxifraga, and Polygonum vivi- 

 parutn. Perhaps the most available plants for the observation 

 of this fact is to be found in the various species of Allium, Cor- 

 dyline viviparum, and Primula Forbesii In which buds or leafy 

 shoots appear among the branches 

 of the inflorescence, and' are easily 

 detachable and propagate the species. 1 



A hybrid between Begonia incar- 

 nata, and B. manicata, which seems 

 to be almost identical with a species 

 from South America known as B. 

 phyllomaniaca, shares with the latter 

 species the capacity for producing 

 buds in great profusion over the en* 

 tire shoot, including the branches of 

 the inflorescence. These may be 

 separated and give rise to new plants. 



426. General Nature and Relations 

 of Reproduction. The reproduction 

 of the plant by either monogenetic, or 

 digenetic spores, may be regarded as 

 special forms of growth, dependent 

 upon, and closely connected with 

 ordinary vegetative growth. So long 

 as conditions favorable to vegetative 

 growth are prevalent, reproductive 

 processes are not carried on so freely, as when adverse in- 

 tensities of various trophic factors prevail. This is noticeably 

 true of the simpler organisms, and is richly illustrated by the 

 activities of the higher plants. . The simple fact does not always 

 appear in the history of any given species however, since the 

 production of digenetic reproductive bodies may have become a 

 rhythmical proceeding that is carried out in the individual regard- 

 less of the surroundings. Reproductive bodies formed either 



Fig. 158. Leaf cutting of 

 Boussingaltia basclloides. The 

 root developed from the leaf has 

 become tuberous. After Vochting. 



1 MacDougal. Nature and Work of Plants, p. 135. 1900. New York. 



