CHARACEM. 



289 



of rather narrow transverse discs. The further development of the contents of these 

 mother-cells of the antherozoids progresses backwards from the end of the filament • 

 the antherozoids are formed in basipetal order in each filament. At first the nucleus 

 of each mother-cell lies in its centre, later it places itself in contact with the septa ; the 

 nuclei then disappear, and their substance becomes mixed with that of the protoplasm, 

 which now forms a central discoid mass in the mother-cell, surrounded by a hyaline 

 fluid (Fig. 205, £■). From this is formed the antherozoid, in addition to which, when 

 it is mature, there is no granular protoplasm ^ The antherozoids begin to rotate even 

 while within their cell, and escape out of it after the rupture of the antheridium ; 

 the filiform antherozoid has in Nitella 2 or 3, in Chara 3 or 4 coils; the posterior thicker 

 end contains a few glistening granules. 



7be Dei'elopment of the Nucules has already been described in detail by A. Braun ; 

 I have also studied it in Nitella Jlexilis and Chara fragilis. In Nitella Jiexilis it springs 

 from the node of the leaf beneath the globule (Fig. 206, B and C) ; its origin is 

 much later than that of the latter. Fig. 209, A, represents a very young nucule, the 

 pedicel of which (/>) bears the 

 smaller nodal cell with the 

 five rudiments of the envelop- 

 ing tubes (/j) (two only are 

 shown here in longitudinal 

 section). Above the nodal 

 cell lies the apical cell (j) of 

 the shoot, which represents 

 the nucule. B represents a 

 iurther stage of development, 

 in which the first of the cells, 

 designated by A. Braun the 

 ' Wendungszelle,' has already 

 made its appearance, and two 

 septa have also appeared on 

 the upper part of each envelop- 

 ing tube ; these upper short 

 cells are raised up by the 



intercalary growth of the tubes, above the apical cell, and form the crown ^ in C 

 and D. The lowest of the cells of the crown each forms a prolongation projecting 

 inwards and downwards, as shown in Fig. 209 C and Z), so that the whole nucule 

 resembles a ' lobster-pot.' The spiral torsion of the enveloping tubes does not 

 begin till a later period ; the coils become gradually flatter while the apical cell of the 

 nucule increases considerably in size and developes into the oosphere (Fig. 206). 

 The development and fertilisation of the nucule of Chara has recently been described 

 in detail by De Bary in the case of C fcetida. Here also it consists, from an early 

 stage of its development, of an axial row of three cells, and five others consisting 

 each of two cells which form an envelope round it. The lowermost cell of the axial 

 row is the nodal cell, the second remains small and colourless, and corresponds to the 

 first 'Wendungszelle' in Nitella. It becomes in this case also, as De Bary's drawings 

 show, separated by a somewhat oblique septum at the base of the apical cell (now the 

 third of the axial row). Originally almost hemispherical, the apical cell grows first 

 of all into the form of a narrow cylinder, and then becomes ovoid; it is provided, 

 until it attains its full size, with a thin very delicate cell-wall ; drops of fat and starch 

 grains accumulate in its protoplasm. Its apex however remains free, and forms a 



Fir.. 209. — Development of the nucule of Kitella Jlexilis (x about 300); 

 -.- ' Wendungszellen.' 



* Compare the opposite view of Schacht, Die Spermatozoiden im Pflanzenreich, 1864, p. 30. 



U 



