246 



PHILOSOPHICAL NOTES ON 



Fig. 92. A branch or leaf of Sargasswn decurreiis* : (a) floriferous 



braucli of petiole. 



leugthening or shortening of the petiole is such a common 

 experience of every grower of plants that I need not dwell on its 

 possibility. Once become axillary, it was only a step for the 

 petiolar branch to become adnate to the stem^ and so lay the 

 foundation, through innumerable variations and trials, for 

 the axillary bud of our days. 



In Sargassum bacciforme (Fig. 93) we already find the 

 petiolar branch became axillary in the shape of a vesicle or float. 

 Finally, when the leaf-branch took to becoming deciduous after 



* PI. 145, vol. 2 and 3, "Harvey's Phyc. Austr." 

 brauchlet with float aiu] receptacle close to each axilla. 



This shows i\, 



