104 MR. HENFREY ON THE DEVELOPMENT OF THE SPORES 



represented in the figures of most of the Ricciacece 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 Sphcerocarpus 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- 

 marmice 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 Ricciacece, in which moreover the elaters 

 are absent f. 



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 J, stated, with regard to 

 Targionia hypopliylla, 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 

 Mr. 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 Riccien, Nov. Act. Acad. Nat. Cur. xviii. 



f 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. 



% Loc. cit. p. 371. § Loc. cit. p. 371-2. 



