EXPLANATION OF THE FIGURES. 461 



PLATE XXI. 



FIG. 



1. Longitudinal section of a fruit-rudiment, X 200. 



2. Section of the apex of a less advanced fruit-rudiment, X 250. 



2*. The same turned round 90, X 250. 



3. A younger fruit-rudiment whose lower part is very highly developed, seen 



from the outside, x 30. 

 3*. Upper part of the same in longitudinal section, x '250. 



4. Longitudinal section of calyptra ; the outer side of the spindle-shaped fruit- 



rudiment is seen, x 60. 



5. Longitudinal section of a young fruit, x 200. 



6. A portion of the layer of mother-cells and of the adjoining tissue of a fruit 



at a similar stage of development. The primordial utricles of the 

 mother-cells are contracted by having lain in water for a quarter of an 

 hour. X 500. 



7. Section at right angles to the longitudinal axis of a fruit, passing through a 



larger portion of the layer of mother-cells, X 150. 



8. A spore-mother-cell out of whose bursting membrane the globular distended 



primordial utricle is emerging, X 300. 



9. Primary mother-cell from the transverse section of a young capsule. The 



cell-contents are beginning to become contracted and constricted, indicat- 

 ing the commencement of the formation of the spore-mother-cells. X 250. 



PLATE XXII. 



1. Spore-mother-cell whose primordial utricle only partly fills the cavity and 



is lying against the wall, x 500. 



2. Two primary mother-cells of the second degree, formed by the division of 



of a primary mother-cell of the first degree by means of a septum 

 parallel to the longitudinal axis of the fruit. Each exhibits only one of 

 the longish ellipsoidal spore-mother-cells enclosed within. One of the 

 latter cells is beginning to divide. The section is at right angles to the 

 longitudinal axis of the fruit. X 300. 



3. Primary mother-cells, each with two free globular spore-mother-cells, in 



which division is about to commence. Direction of the section as in 

 the last figure, x 300. 



4. Longitudinal section through some primary mother-cells of a somewhat 



more developed fruit, X 200. 



5. Young spore from the same, X 500. 



Eigs. 6 21. Gymnostomum pgriforme. 



0. Longitudinal section through the upper end of a fruit-rudiment whose 

 apical cell has ceased to multiply in the direction of its length, and 

 whose expansion in breadth underneath the apex is just beginning. 

 The top of the specimen was destroyed by the section ; the representa- 

 tion of the boundaries of the cells at that part is shown hypothetically 

 by dotted lines, x 400. 



