186 HOFMEISTER, ON 



to recognise. There can however be no doubt that after 

 some time the antheridmm is composed of a cylindrical or 

 angular, almost cubical, central cell of large size, very rich 

 in granular protoplasm, supported by one cylindrical or two 

 semi-cylindrical cells, covered by a cell having the form of 

 a segment of a sphere, and surrounded laterally by a girdle, 

 which in most cases looks at first sight like a simple 

 annular cell, or two such cells standing one over the other, 

 but which, after more careful examination, and especially 

 after treatment with a saccharine solution and iodine, may 

 often be seen to be composed of several cells, from two to 

 four in number, lying in one plane. 



Those states of the antheridia which, judging from their 

 size and their position on the prothallium, are intermediate 

 between the condition just mentioned and the unicellular 

 condition, may be distinctly recognised by the sharply de- 

 fined, circular boundary line of the apical cell; and, less 

 distinctly, by the appearance of the central cell which is rich 

 in protoplasm. In some young antheridia the best object- 

 glasses especially when combined with the use of a solution 

 of sugar and iodine exhibit the lines of contact of the cell- 

 walls with the outer surface of the antheridia. These lines 

 run obliquely downwards, usually in a left-handed spiral 

 which describes about a sixth part of a circumference (PI. 

 XXIV, fig. 9). The analogy to be derived from the pro- 

 cess of development of the antheridia of the Muscineae ren- 

 ders it probable that the large central cell is formed by the 

 production of an excentrical, inclined, longitudinal septum 

 in the young antheridmm, followed by the production of 

 another excentrical septum cutting the latter at right 

 angles, and the subsequent formation of a longitudinal 

 septum cutting both the above at an angle of 45, such 

 formation taking place after the apical cell of the antheri- 

 dmm has been isolated by a strongly inclined almost hori- 

 zontal septum cutting the primary longitudinal septum. 

 Where the central cell is surrounded by two zones of en- 

 veloping cells it is manifest that the two zones originate in 

 the transverse division of the primary single zone. 



The structure of the prothallia and antheridia of all the 

 Polypodiacese which have been yet examined is identical in 



