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Transactions. 



detached from their parent prothalli. I am thus able to give a connected 

 account of the development of the young plant. The earliest stages, in 

 which the young shoot has just broken through the surface of the prothallus, 

 and before a vascular strand has made its appearance (see fig. 61), has 



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Fig. 62. — Section through foot of same young .plant let as shown in fig. 61, showing 



outgrowth of epidermal cells of foot. X 74. 

 Fig. 63. — Transverse section of young plantlet similar to that shown in fig. 68, showing 

 PJ initiation of secondary apex of growth. X 64. 



Fig. 64. — Very young detached plantlet, showing apex of growth, and fragment of 



prothallial tissue attached to foot. X 18. 

 Fig. 65. — Very young detached plantlet, showing foot and both primary and secondary 



apices of growth. x 16. 

 Ftg. 66. — Young developing plantlet attached to prothallus ; secondary apex of growth 



not yet developed. X 8. 



been described at the end of the last section. The shoot-apex in this 

 particular plantlet had already been differentiated, though precisely at 

 what stage in the development of the embryo I cannot say for certain. 

 The subsequent elongation o the originally spherical shoot takes place 

 at this apex. In figs. 64 and 65 are shown two early stages in the develop- 



