BOOKS AND CURRENT LITERATURE 



Prothallia of Tmesipteris.^ — In a Dacrydium-Podocarpus forest 

 of Stewart Island, whose vegetation, in general appearance, "is sug- 

 gestive of an age when Gyinnosperms and Pteridophytes were dominant 

 rather than Phanerogams," and in forests of Western New Zealand, 

 Holloway^ has discovered numerous prothalli of Tmesipteris growing in 

 humus on fallen tree trunks and as epiphytes on the* tree ferns Dick- 

 sonia and Cyathea. The tree fern Dicksonia, because of favorable ex- 

 ternal anatomy, affords a comparatively easy substratum to search, 

 and the writer was able to find between 60 and 70 gametophytes in 

 various stages of development. Search for the prothalli is rendered 

 difficult on account of their subterranean location, the dense growth 

 of Tmesipteris due to vegetative reproduction, and the germination of 

 spores only under the most favorable conditions, and but few of these 

 rare and important stages in the life cycle of Tmesipteris have been 

 reported. 



The prothallus is cylindrical in form, brown at first l)ut becoming 

 darker with age, 1 to 18 mm. in length; it is covered with numerous 

 long, golden-yellow rhizoids, never reaches the light and is destitute of 

 chlorophyll. The unbranched, carrot-shaped form eventually branches 

 dichotomously or trichotomously, and one of the branches thus formed 

 may branch again. Figures showing the unbranched prothallus re- 

 semble in outline the illustration of the gametophyte of Helminth- 

 ostachys, while those of the branched forms appear like the game- 

 tophyte of Ophioglossum figured in Campbell's Mosses and Ferns. A 

 mycorhiza is present in the central portion of the prothallus, but the 

 fungus-infested legion does not form a definite zone like that of Ly co- 

 podium gametophytes. The condition of the prothalli found indicates 

 that the spore germinates into a filament about three cells in length 

 which gives rise to a mass of cells probably comparable to the primary 

 tubercle of Lycopodium cernuum, but instead of a filament, this mass 

 is succeeded above by another larger swelling, and so on to the apex of 

 the gametophyte which is bluntly rounded. Growth of the gameto- 

 phyte is not checked by the production of a sporophyte. 



1 HoUoway, Rev. J. E., D.Sc. The prothallus and young plant of Tmesip- 

 teris. Trans, of the New Zealand Institute, Vol. L, 1917. 



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