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Transactions. 



from the spore is now of im}3ortance only in the initial establishment of 

 a certain species in new localities, as, for example, at the edge of the 

 retreating forest, and that the subsequent peopling of these localities by 

 such species, and their continued existence and spread, is due to vegeta- 

 \i\Q propagation alone.* 



III. External Features op the Prothalli. 



L. Billardieri. 



The prothallus of this species has recently been described in detail 

 by Miss Edgerley (8, p. 104). External examination of my own specimens 

 showed that it conforms more or less closely to the type of L. Phlegmaria. 

 Miss Edgerley states that the internal structure also, except in one point, 

 closely resembles that of the latter species. In each prothallus there is 

 a central mass of tissue, in some cases compact and bulky, in others 

 more extended and thin, from which long club-shaped processes arise 

 (figs. 1-11, on p. 277). The prothallus is dingy white in colour, the ends 



Figs. 1-6. — Lycopodium Billardieri. Complete prothalli. 



4 and 6, X 4. 



1, 2, 3, and 5, X 8 ; 



of the processes being more translucent in appearance. Rhizoids arise 

 OTer the whole of the prothallus except at the extreme ends of the processes. 

 Besides the rhizoids, numerous short and thin processes, each of which 

 is several cells in length but only one in thickness, arise from the 

 surface of the prothallus. These will be probably the paraphyses de- 

 scribed by Treub in L. Phlegmaria and by Miss Edgerley in this species. 

 The youngest prothallus found by me (fig. 1) was 1 mm. in total length, 

 and the largest from 12 mm. to 15 mm. (figs. 4-6). 



♦Where the land-surface was deeply covered by volcanic ash during the eniption of 

 Tarawera in 1886, L. cernuum was growing in abundance some years ago near certain 

 stream's of hot water. Colonies of this description must have originated from spores, 

 but, unfortunately, no exact data are available as to the first appearance of young plants. 



