104 MR. HENFREY ON THE DEVELOPMENT OF THE SPORES 
represented in the figures of most of the Ricciacee in Lindenberg’s Monograph*. 
While the enlargement of the nascent sporangium tends to fill up the cavity of the pistil- 
lidium, the single layer of cells composing the wall of the latter is developed still more 
rapidly than the sporangium ; its elongated neck disappears, and it is found in the nearly 
ripe fruit as a loose cellular envelope immediately enclosing the sporangium ; when quite 
ripe it bursts above, exhibiting irregular teeth. The envelope of the globular sporangium 
of Spherocarpus terrestris appears to me identical in its nature, but it remains green 
and does not burst: a little orifice in the apex, corresponding to the base of the neck-like 
portion of the pistillidium, may permit the escape of the spores ; otherwise they can only 
become free by the decay of this involucre. 
The walls of the sporangia of Marchantia are composed of a single layer of cells, at 
first almost cubical, and filled with chlorophyll-vesicles ; but as they enlarge they become 
elongated in the vertical direction, the chlorophyll disappears, and spiral fibres, or more 
frequently annular bands, make their appearance upon the walls. These bands are of a 
flattened riband-like form, and of a yellow colour, the membrane of the walls of the 
perfect cells is hyaline, and the cavity contains only a few yellow granules. This structure - 
of the wall of the sporangium of annular fibrous cells is analogous to that of the Junger- 
manme and to the spiral tissue of anthers, and is for a similar purpose, namely by its 
elasticity to cause the rupture of the mature parts as they become dried by evaporation. 
No similar elastic tissue presents itself in the Riceiacee, in which moreover the elaters 
are absent ft. | 
In all the foregoing points, my observations agree perfectly with those of M. Mirbel. 
Before proceeding to detail what I have seen in the development of the spores, it will be : 
as well to give an account of what had been observed by preceding authors. 
Mr. Griffith, in a note appended to M. Mirbel’s first memoir t, stated, with regard to 
Targionia hypophylla, that “in the young ovaries the elaters are not visible, and the 
seminules, united by a gelatinous substance, form as it were a continuous mass. They 
then seem to be vesicles filled with corpuscules, although when mature each is evidently 
a cellular body.” 
M. Mirbel$ remarks on the same plant :—“ The nascent seminules are contained in the 
cells of a tissue which fills the young ovary; each cell contains three or four seminules. 
As the ovary advances in age, its internal tissue becomes dislocated, and is broken up 
into as many distinct utricles as there were cells, so that the little groups of seminules 
each have a utricle for an envelope. 
“ The seminules, young or old, are themselves simple utricles, which contain colourless 
spherules attached to their walls. This observation does not agree with the opinions of 
- Griffith ; according to him, the mature seminules are formed of cellular tissue. 
“ The elaters do not display themselves until some time after the dislocation of the tissue. 
They are slender, colourless, perfectly closed tubes, always with blind terminations (en 
* Lindenberg, Monographie der Riceien, Nov. Act. Acad. Nat. Cur. xviii. 
T According to M. Mirbel, the cellular tissue of the sporangium of Targionia (which has elaters) is not annulated, 
but the cells have half-rings on the internal and lateral walls, like the Jungermannice. 
T Loc. eit. p. 371. $ Loc. cit. p. 371-2. 
