366 SCIENCE PROGRESS. 



resemble the filamentous prothallus of Trichomancs (Goebel, 

 Flora, p. 92, etc., 1892), still the archegonium of the former 

 appears to be a typical Moss archegonium, while that of 

 the latter is as typically that of a Fern. In dealing with 

 the classification of the higher plants the principle has been 

 observed of giving priority to the reproductive organs, and 

 using the comparison of the vegetative organs as secondary. 

 There is no sufficient reason for departing from this method 

 in the present case ; if the attention be fixed on the arche- 

 gonia, the distinction between Mosses and Filmy Ferns re- 

 mains as wide as ever. Comparative study has taught that 

 the archegonium is a relatively constant organ for the larger 

 groups of plants, and its diagnostic importance should not be 

 subordinated to the claims of the plastic vegetative gameto- 

 phyte. 1 In addition to this there remains the vast difference 

 between any Moss sporogonium and any Filmy Fern ; and 

 when this is added to the difference of archegonia and of 



1 It may here be noted that I have had fruiting specimens of Bux- 

 baumia under observation during the summer of 1895. When they came to 

 my hands in May, the sporogonia were of various ages : examination of 

 a number of plants showed that, though the young sporogonia must have 

 been making large demands for nutrition, no chlorophyll-containing tissue 

 was present on those gametophytes which I examined ; but there was as 

 usual a very extensive system of rhizoids : there was chlorophyll in the 

 older sporogonia. 



Now the sporogonium is a large one, and the question is whence it 

 obtains its nutritive supply. Its own powers of assimilation are not great, 

 if we may judge from the extent of its chlorophyll-containing tissue, though 

 this is larger than in most Mosses. But the question presents itself in its 

 most acute form when the sporogonium is young, and this limited assimilat- 

 ing tissue not yet matured. In the absence of assimilating tissue of the 

 gametophyte (as far as I have been able to observe on my specimens), the 

 only source of supply which I can suggest is from saprophytic action of the 

 rhizoids, a suggestion which Haberlandt has already made as the result of 

 observation of their details. 



It is true that after cultivation for some weeks under a bell glass, well 

 exposed to light, there was a slight development of chlorophyll-containing 

 cells on the gametophyte, but as these only appeared subsequently, at a 

 time when the sporogonia were making no further demands for nutrition, 

 they cannot be considered as having any direct bearing on the question. 

 Though not conclusive, the evidence seems strongly in favour of sapro- 

 phytic nutrition of Buxbawnia. F. O. B. 



