Holloway. — The Prothallus and Young Plant of Tmesipteris. 29 



larger leaves of the characteristic form take their place. Both ends of 

 the young rhizome may in some cases emerge from the humus as aerial 

 stems (fig. 73). The actual apex of the young aerial shoots is slender 

 and sharply conical (figs. 5, 73, 74), and even in surface view under a low 

 power of the microscope the single apical cell can be seen. In longitudinal 

 section the apical cell and the order of segments cut off from it is almost 

 diagrammatically clear (fig. 77). The broader apex of young rhizomes also 

 shows a single apical cell (fig. 76). In several instances young plants of 

 a considerable size, showing differentiation into both subterranean and 

 aerial portion, were found still attached to their prothalli, the latter being 

 in some cases firm and health v (figs. 5, 73), and in others old and withered 

 (figs. 9, 10). 



Fig. 67. — Young detached plantlet. showing fragment of prothallial tissue attached to 



foot ; secondary apex of growth not yet developed. X 8. 

 Fig. 68. — Young plantlet attached to prothallus, showing secondary apex of growth. 



X 5. 

 Fig. 69. — Young detached plantlet, showing foot and secondary apex of growth. X 7. 

 Fig. 70. — Young detached plantlet, showing foot and also primary and secondary apices 



of growth on either side of foot. The two apices are not inclined to one 



another at an angle. X 8. 

 Fig. 71. — Young detached plantlet, showing foot and also primary and secondary 



regions of rhizome on either side of the foot. X 6. 

 Fig. 72. — Young developing complete plant, showing foot and also lateral bud; the 



latter and the two apices are swollen. X 4. • 



Development op the Vascular Anatomy. 



The anatomy and morphology of the adult plant of Tmesipteris has 

 already fairly recently been described by Miss Sykes (1908), so that there 

 is no need for me to go over this ground again. Miss Sykes's material 

 came from New Zealand, and she notes that it comprised two forms which 



