HoijI.oway. — Studies in the New Zealand Sj)ec/es of Lycopodimn. 199 



bulk of the prothallus or to the fact that, as in L. volubile, it occasionally 

 grows at the surface of the ground and develops chlorophyll. The different 

 species, however, show certain characters, more especially in the structure 

 of the fungal zones, in which they differ from the other species of the same 

 type. These might be viewed as variations from the two main stocks repre- 

 sented by L. clavatum and L. complanatum, or they may be taken as 

 indicating that the adaptation of the prothallus to the subterranean, wholly 

 saprophytic mode of life has occurred independently in a number of species. 



A comparison of Bruchmann"s account of the prothallus of L. clavatum 

 with that of Lang shows that, although in the main the two descriptions 

 are very similar, there are yet certain particulars in which they differ. 

 These refer more particularly to the main fungal and store tissues. It will 

 be worth while to notice these details, in view of the fact that, as will be seen 

 below, some of the distinguishing details in the two New Zealand species are 

 remarkably characteristic. Some of the differences manifest between Bruch- 

 mann's and Lang's accounts and figures are to be explained by the fact that 

 the longitudinal sections which the latter figures and describes are not 

 median. Lang himself in a footnote mentions that the first-formed conical 

 projection at felie base of the prothallus was not at first noticed by him 

 and hence does not appear in his figures. On account of this, the layer of 

 flat, elongated cells belonging to the central core, which Bruchmann describes 

 as lying next to the starch-containing store tissue where the latter abuts 

 on to the centrally placed core of large-celled empty tissue, does not appear 

 in Lang's figures and is not mentioned by him, for in the sections on which he 

 bases his description it was, of course, cut transversely. Also, Bruchmann's 

 figures show a very much thicker subepidermal cortical fungal zone than do 

 Lang's — at least, towards the upper half of the prothallus. Again, Bruch- 

 mann speaks of the starch-containing store cells as polyhedral in shape, 

 but Lang says that they are not infrequently elongated in the same 

 direction as those of the palisade layer. Bruchmann figures the palisade 

 layer as a very clearly marked one in which the single row of palisade cells 

 is very much elongated in a direction at right angles to the surface, but in 

 Lang's figures the cells are much shorter and are sometimes in two rows. 

 Now, all these differences can be accounted for by the fact that Lang's 

 sections, not being exactly median, have cut the various cell-layers some- 

 what obliquely. These differences in the two accounts, therefore, must 

 not be taken to show that the structure of the prothallus of L. clavatum is 

 in a variable condition. A more important difference between the two 

 accounts lies in the fact that Lang describes the presence of the fungus in 

 the starch-containing store tissue as penetrating not within the cell-cavities 

 but in the cell-walls, whereas Bruchmann says quite definitely that it stops 

 short with the palisade layer, and in his figures he shows it to be altogether 

 absent from the store tissue. Ls it possible that the fungus enters this tissue 

 in rather old prothalli only, and that this must be held to account for the 

 difference ? Lang's description in this particular agrees with my own 

 observations on the prothallus of L. volubile and L.fastigiatum. There is no 

 need for me here to enter into any of the other details of the prothallial 

 tissues. 



In the prothallus of L. volubile the most characteristic feature is the 

 enormous development of the palisade layer. This layer constitutes 

 generally by far the greater bulk of the whole prothallus. The cortical 

 fungus layer corresponds with that of L. clavatum except that in the New 

 Zealand species it is only from two to four cells in width. In a median 



