On the Germination of the Spores of Ferns. 347 



vesicle, in the interior of the embryo-sac. The other end, pro- 

 jecting into the canal, dies away. This phenomenon must not 

 be confounded with the forcible tearing of the spiral filaments 

 just alluded to. Through the union of the germinal vesicle and 

 the embryo originates the embryonary globule, which is only 

 attached below to the bottom of the cavity containing the em- 

 bryo-sac by a very delicate filiform suspensor. With the growth 

 of the embryonary globule the colourless nuclear papilla dies, 

 dries up, and the canal in particular becomes coloured brown. 

 Tn this condition it persists for a long time upon the now ex- 

 panding cavity of the nucleus. Usually only one of the nume- 

 rous naked ovules produced upon the pro-embryo developes its 

 embryo. This need not appear wonderful, since similar examples 

 are not wanting in the vegetable world, as in many Palms one 

 alone of the three original cavities is regularly perfected. A spe- 

 cial reason may be looked for here in the minute size of the pro- 

 embryo, which does not afford sufficient nutriment for several 

 embryos. With the further development of the one embryo the 

 other rudimentary ovules die. In these the foramen of the pa- 

 pilla expands, and allows the dead spiral filaments and the rest of 

 the contents to escape. The canal, and especially the cavity for 

 the embryo-sac, then exhibit a brown colour. The latter may 

 be most distinctly recognized in this condition. In vegetating 

 ovules, on the contrary, this part can only be observed by a most 

 careful extraction of the single organ. For while on the one 

 hand it is covered by the still erect nuclear papilla, the detection 

 of it is on the other hand rendered impossible by the want of 

 any peculiar colour or otherwise distinguishing outlines. Of all 

 the species which I have examined, Polypodium aureum is, next to 

 Pteris serrulata, the best-adapted. The impregnation follows 

 exactly the above-described type in all families, genera and spe- 

 cies ; an exceptional occurrence is the appearance, on the margin 

 of the pro-embryo, even in its earliest stage, of a spiral-filament 

 organ differing somewhat in structure, as it loses its uni-cellular 

 aspect. Five or six parietal cells are formed which inclose in the 

 middle a space either filled with spiral filaments, cellules or hol- 

 lows. These structures must be regarded as monstrosities of the 

 spiral-filament organs, since they occur abnormally and on in- 

 dividuals which never produce an embryo. Such an infertile 

 pro-embryo either decays soon after its origin, or, passing into a 

 succulent state of growth, appears much larger than is natural. 

 In this condition it acquires a resemblance to a Marchantia, and 

 usually produces a great number of abortive ovules." 



This extract has reached such a length that we have not space 

 to give an account of the author's description of the develop- 



