THE HIGHER CRTPTOGAMIA. 175 



branched and divided by septa, differing herein consider- 

 ably from the simple radical threads of prothallia. Such 

 of the above-mentioned processes as are rich in chlorophyll 

 are divided by septa perpendicular to the longitudinal axis ; 

 those which are deficient in chlorophyll, by oblique septa. 

 These widely-creeping cellular threads have the capacity of 

 producing new expanded pro-embryos, by enlargement and 

 division of the terminal cells. 



In individual cells of the lobes of the embryo, usually in 

 those very near the base, a multiplication commences differ- 

 ing essentially in direction and in kind from that hitherto 

 spoken of. A hemispherical knot of cellular tissue is pro- 

 duced, which by degrees becomes cylindrical, and which, 

 developing, as it does even at an early period, some rudi- 

 mentary leaves, may be recognised as the shoot of a moss 

 (PL XVIII, fig. 10). The arrangement of the cells of the 

 leaves brings to mind Sphagnum ; a suspicion which is 

 reduced to certainty by the characteristic thickening layers 

 of the leaf-cells which appear in the fifth leaf. I find the 

 phyllotaxis to be from the beginning § (PL XVIII, fig. 10). 

 Rootlets springing from the leafy root are not to be found 

 in Sphagnum acutifolium. 



Hedwig's observations* were the commencement of an 

 accurate knowledge of the sexual reproduction of mosses. 

 He pointed out the antheridia as the male organs, recognised 

 their structure, and observed the escape of their contents. 

 He figured the archegonia as flask-shaped bodies, closed 

 when young, and afterwards opening at their apex. He 

 also pointed out the conversion of the ventral portion of the 

 archegonium into the calyptra, and the formation of the 

 fruit-rudiment within it. Lastly, he showed by experiment 

 that the spores of the mosses are their true seeds. He 

 sowed the spores of Gymnostomum pyriforme, and observed 

 their germination, and the development of the inner spore- 

 membrane into a cellular thread, or, as Hedwig called it, a 

 cylindrical cotyledon (1. c, 153, pi. xvi, fig. 9). After some 

 time scales were seen on these threads, which scales, when 

 examined with the microscope, proved to be young plants, 

 the bases of which were attached to branched pro-embryonal 



* "Iheoria gcnerationis,' ed. ii,p. 134, et seq. 



