THE HIGHER CRYPTOGAMIA. 169 



Arcliidium are, therefore, not altogether a departure 

 from the typical development of moss-fruit, but are rather, 

 with regard to the first point, a diminution, and with 

 regard to the second, an increase, of the growing power 

 usual in the allied forms.* 



The antheridia do not differ essentially from those 

 of the species of Phascum. The spermatozoa are rather 

 large ; they exhibit, very clearly, the two cilia shown by 

 Thuret, to exist in the mosses generally. The structure of 

 the unimpregnated archegonia is distinguished from that in 

 Phascum only by the slight extent of the longitudinal deve- 

 lopment of the lower part (PI. XXIII, fig. 1). I cannot 

 confirm P. W. Schimper's statement as to the pleuro- 

 carpus fructification of Archidium. I find rather that the 

 position of the archegonia and fruit exactly agrees with 

 that which obtains in Phascum. The germinal vesicle is 

 usually attached to one of the side walls of the central cell 

 of the archegonium (PI. XXIII, fig. 1). After impregna- 

 tion the germinal vesicle enlarges to a remarkable extent, 

 considerably expanding the ventral cavity of the archego- 

 nium, and pressing together the adjoining cells (PI. XXIII, 

 fig. 2). The cell-succession of the fruit-rudiment is that 

 which is common to all mosses, depending upon the re- 

 peated division of the apical cell, by septa inclined alter- 

 nately in two different directions (PI. XXIII, fig. 3). 

 The upper half of the fruit-rudiment soon increases in 

 thickness, and ruptures the calyptra on one side, dis- 

 placing it laterally (PI. XXIII, fig. 4). 



In the interior of the fruit-rudiment, underneath the 

 second cellular layer (reckoning from the outside inwards), 

 layers of cells parallel to the outer surface become discon- 

 nected : an intercellular space is formed, having the shape 

 of an ellipsoidal covering, truncate at either end (PI. XXIII, 



* Schimper attempted to explain the nature of the ripe fruit of Arcliidium 

 (PL xxiii, f. 11) by supposing that the whole of the interior of the fruit-rudi- 

 ment became converted into mother-cells, and that only one spore was formed 

 in each of them ('Reek, sur les Mousses,' Strassburg, 1848, Bryol. Europ. 

 1st ed., p. 2). In the ' Vergl. TJntersuchungen,' I have objected to the above 

 view, on the ground that imperfectly ripe spores exhibit a junction in fours. 

 The observations given above (which were first published in the ' Reports of 

 the Royal Academy of Saxony,' 1854, p. 102) were made upon living plants, 

 kindly furnished by Messrs. Schultz, Bitsch, Tulasne, and Durien. 



