256 HOFMEISTER, ON 



the fragments of the stipules. The first fronds of these 

 shoots have no lamina ; they are entirely stipuheform. 



Development of the fruit and spores. — Although 

 much variety exists in the process of formation of those 

 organs of ferns which surround and cover the sori, ne- 

 vertheless the development of the capsules of the Poly- 

 podiaceae exhibits, as far as present observations extend, 

 a marked uniformity. At the place of attachment of 

 the sorus the rudiments of the capsules are developed 

 (contemporaneously with the appearance of the indusium 

 where the latter is present), under the form of short multi- 

 cellular hairs. The terminal cell of each swells to a globular 

 form, and, by the effect of a series of cell-divisions, assumes 

 the form of a bod} r consisting of a single central cell and 

 a peripheral cellular layer. The central cell is the primary 

 mother-cell of the spores. By division in all three direc- 

 tions of space it is transformed into a globular mass of 

 polyhedral cells — the spore-mother-cells — the walls of which 

 become somewhat thickened. Whilst the internal cavity of 

 the young sporangium becomes enlarged by the expansion 

 of the peripheral layer, the walls of the spore-mother-cells 

 swell, and the latter become disconnected, and assume a 

 globular form. They then divide into four special-mother- 

 cells, which in certain species are situated at the angles 

 of a tetrahedron, in others are arranged in a decus- 

 sate manner. A spore is formed in each of these 

 special mother-cells. The membrane of the primary 

 mother-cell is still existent at the time of the commence- 

 ment of the individualization of the spore-mother- cells, and 

 can be detached from the peripheral cellular layer.* This 

 development of the capsule has been observed by Schacht, 



* Schacht, 'Bot. Zeit.,' 1849, figs. 6, 7. The membrane of the primary 

 mother-cell, like those of the mother-cells, is somewhat distended; the 

 latter appear to be suspended freely in the former. Schacht was thus led to 

 assume that the mother-cells originated by free cell-formation in the primary 

 mother-cell (1. c, p. 544). Schacht's statement that the nucleus of each 

 primary mother-cell separates by division into four secondary nuclei, is not 

 confirmed by the observations which 1 have made upon Asplenium filix-femina 

 and Cystopteris fragilis. In the former I found at first two secondary nuclei in 

 the place of the primary one, and afterwards four tertiary ones in the place of 

 the secondary ones. It appeared to me that here also the dissolution of the 

 primary nucleus of the mother-cell preceded the formation of the nuclei in 

 daughter-cells. 



