THE PROTHALLUS OF TMESIPTERIS TANNENSIS. 791 



The very early stages in its formation were not found, but the series shown in 

 figs. 8, 9, 10, and 11 gives a fair idea of the development. Fig. 8 represents a section 

 through the antheridium, and here we observe the nature of the wall, which even in 

 this early stage shows seven cells in section surrounding the spermatogenous tissue. 

 A little later stage is shown in fig. 9 : here eleven cells are to be seen in a single 

 section of the wall, and this completely surrounds a large mass of sperm mother cells. 

 In fig. 7 we have represented two antheridia in section lying close together. In 

 fig. 10 the antheridium is shown not in section but in surface view, and it contains 

 a very large number of spermatocytes. This figure also shows the relative size of the 

 mature antheridia in relation to the mature archegonia, which are situated close 

 beside it. At the very apex of the spherical antheridium the main wall cell is larger 

 than the others, and, judging from figs. 10 and 11, it is this cell which becomes free, 

 forming an exit for the spermatozoids. The mature spermatozoids were not found, 

 but if one may judge from the appearance of the nuclei in the sperm mother cells 

 shown in figs. 9 and 10, they must be of considerable size and quite numerous. 



Old antheridia from which the spermatozoids had been discharged were frequently 

 met with, and some of these are shown in figs. 2 and 3. A more highly magnified 

 example is shown in fig. 11. From the large number of spermatozoids that are 

 evidently formed and the close proximity of the antheridia to the numerous arche- 

 gonia, fertilisation is easily accomplished. From the evidence to hand one cannot 

 say definitely whether these spermatozoids are multiciliate or biciliate. One would 

 expect to find the former condition. As I now know how to obtain the prothalli, I 

 can safely promise a more thorough investigation of spermatogenesis and fertilisation 

 in the near future. As far as this brief description has gone, however, it is sufficient 

 to convince one that there is not a very strong resemblance of the antheridium of 

 Tmesipteris to either Lycopodium or Equisetum. 



The Archegonia. 



The archegonia of Tmesipteris are quite small in size and very simple in structure. 

 As already stated above, there is clearly no differentiation of a vegetative and repro- 

 ductive region of the prothallus. Almost any part of the prothallus apparently bears 

 archegonia. They were found at both ends and on all sides, as shown in figs. 3 and 6. 

 Fig. 3 is drawn from an entire prothallus, and one surface view shows fourteen 

 archegonia associated with three antheridia. On the opposite side of this same 

 prothallus, which was studied by turning the slide over, no less than sixteen 

 archegonia were observed associated with antheridia. Fig. 6, which represents a 

 fairly median section through another prothallus, shows clearly that the archegonia 

 may be distributed on at least two opposite sides. In this section we may see eight 

 archegonia in the upper side of the figure and four on the lower side. In fig. 2 we 

 have represented an entire prothallus with only two archegonia showing, so that 



