Hollowat. — Prothallus, JL-c, of Tmesipteris. 



393 



buds arise from two cells, but the bud shown in general view in fig. 26, 

 judging from the old point of attachment at its base, seems to have arisen 

 from a single cell. The two largest buds found (figs. 26. 27) were some- 

 what brown in colour in their lower portions, the cell-walls being strongly 

 marked as in the case of prothalli formed from the spores. The cells in 

 this region showed the presence of fungal coils. From fig. 22 it is clear 

 that the fungus had infected this particular bud through a rhizoid Nothing 

 was found to illustrate the further history of these structures. 



25 



Fig. 22, 23. — -Young prothallial adventitious buds in longitudinal section. X 75. 

 Fig. 24.— Longitudinal section of the bud marked X in fig. 23, showing its apical 



cell. X 75. 

 Figs. 25-27. — Prothallial buds of different ages in general view. Fig. 25 X 75; 



fig. 26 X 44 ; fig. 27 X 30. 



Darnell-Smith notes (3, p. 87) that the prothallus of Psilotum (presum- 

 ably P. triquetrum) frequently bears small bulbils which are carried upon 

 short stalks one cell in width. I have found on old rhizomes of P. tri- 

 quetrum collected on the scoria islet of Rangitoto, Auckland Harbour, an 

 abundance of the bulbils which were first described by Solms Laubach (14). 

 But no corresponding structures have been observed on the rhizomes of 

 Tmesipteris, so that it is interesting to find that the prothallus of the latter 

 bears under certain conditions small superficial buds. The occurrence of 

 adventitious buds in both generations of the Psilotaceae increases the 

 similarity between them noted above. 



