THE HIGHER CRYPTOGAMIA. 257 



in Pteris serrtdata, Aspleninum Petrarice, and Scolopendrium 

 officinarum ; and by myself in JsjjI. JUioj-femlna, and 

 Cystopteris fragilis. H. v. Mohl, in 1833, described 

 the development of the spores in special-mother-cells 

 (four being contained in each mother-cell), whose mem- 

 branes possess a remarkable power of distension (see 

 'Flora,' 1833, B. i- ' Vermisclite Schriften,' p. 69). In 

 the families of ferns other than the Polypodiaceae, few ob- 

 servations have been made. I may remark here, that I 

 have clearly seen a single central cell in very young 

 sporangia of Osmunda regalis. In this respect, therefore, 

 ferns seem to agree with the rest of the vascular crypto- 

 gams, viz., that a single cell situated in the interior of the 

 young sporangium represents the primary mother-cell of all 

 the spores. 



Historical Beview. The reproduction of ferns by means 

 of spores was first pointed out by Morison, who states (' His- 

 toria plantarum,' Oxford, 1699, iii, p. 55) that after sowing 

 the spores of Scolojjendrium officinariim upon moist ground in 

 the shade, he obtained in the following year numberless little 

 plants of the same species, with delicate mid at first 

 roundish leaves. Ehrhart first made known with certainty 

 that the production of the perfect fern is preceded by the 

 development of a deeply two-lobed leaf-like body, upon 

 the under side of which, between the indentations and the 

 hinder end, the perfect fern is attached (' Beitrage/ iii, 

 Hanover, 17S8, p. 75). For the first accurate micro- 

 scopical investigations of the germination of fern-spores we 

 are indebted to Kaulfuss, who clearly and accurately 

 described the rupture of the outer spore-membrane, the 

 protrusion of the inner one, and the development of the 

 prothallium ( ( Das Wesen derFarrn-krauter,' Halle, 1827, 

 p. 61). The sexual organs of the prothallium entirely 

 escaped his observation, as well as the enclosure of the 

 young embryo in the tissue of the prothallium. The dis- 

 covery of this fact is due to Bischoff (' Handb. botan. Tcr- 

 minologie,' b. ii, Niirnberg, 1842, p. 640), who states that 

 a wart-like excrescence originates on the back of the pro- 

 thallium underneath its indentation, and that out of this 

 excrescence the first frond breaks forth in an upward 



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