THE HIGHER CRYPTOGAM IA. 37 



plication of the cells of the sheath in a longitudinal direc- 

 tion, when the sheath has attained a length equal to a 

 fourth or a third part of the stalk of the young fruit which 

 is still enclosed in its calyptra (PL V, fig. 13). At an early 

 period, even before the expiration of the third month from 

 the commencement of the rudiments of the fruit, a diffe- 

 rentiation of the tissue appears in its upper swollen end, 

 i. e. the future capsule. The cells of the outer surface 

 divide by septa perpendicular to this surface, and then 

 again by partitions also perpendicular to the arched outer 

 surface, cutting the last-formed septa at an angle of 90°. 

 The inner cells take no part in this division ; they appear, 

 therefore, eight times larger than the others ; in longitu- 

 dinal and also in transverse sections, the boundary of each 

 pair of cells of the outermost layer coincides with that of 

 one of the adjoining inner cells (PL V, fig. 11). At the 

 same time the walls of the inner cells of the young capsule 

 begin to thicken. The substance of the thickened walls 

 swells up very rapidly and extensively in water ; to such an 

 extent that, in cutting through a young fruit placed in water 

 upon the stage of the microscope, the cells of the interior 

 of the capsule immediately protrude laterally beyond the 

 w T all of the capsule. The swollen gelatine is dispersed in 

 the water ; the primordial utricles of the cells become free, 

 and assume a spherical shape (PL V, fig. 12). In order 

 to get an insight into the structure of the interior of the 

 young capsule, it is indispensable that it should be examined 

 in rectified spirit of wane. With tincture of iodine the 

 entire mass of its cell-walls becomes coloured a vinous red 

 or violet. Even after the differentiation of the wall from 

 the inner tissue of the young capsule, the cells of both in- 

 crease considerably. The cells of the low 7 er part of the wall 

 divide by septa parallel to the outer surface ; consequently, 

 at the spot where the wall of the capsule adjoins the fruit- 

 stalk, that wall consists of two layers of cells. On the other 

 hand, the cells of the wall of the upper part and of the 

 apex of the young capsule divide exclusively by septa per- 

 pendicular to the outer surface (compare fig. 11 of PI. V 

 with fig. 13). At the same time the cells of the interior, 

 especially those at the boundary of the wall of the capsule, 



