72 



SECOND GROUP.— MUSCINEAE. 



moss-stems arise. Schimper considers the protonemal patches formed by Polytrichum 

 nmium and P. aloides on banks in lanes, and those of Schistostega osmundacea in 

 dark caves to be also growths from rhizoids. 



But rhizoids may produce leaf-buds directly, and in this respect are just like a 

 protonema; if the buds arise on subterranean ramifications of the rhizoids (Fig. 123, 

 B), they are small tuber-like bodies of microscopic size filled with reserve food- 

 material, which often remain dormant, till, as happens occasionally, they come to the 

 surface where they then proceed to develope ; such buds are found in Barhula 



Fig. 125. Tetraphis pellucida. A a plant of the natural 

 size forming gemmae. B thie same magnified ; y the cup in 

 which the gemmae are collected. C longitudinal section 

 through the summit of ^ ; * the leaves which form the cup. 

 A' the gemmae in various stages of de\'elopment ; the older 

 gemmae are torn from their stalks by the growth of the younger 

 and thrust beyond the edge of the cup. D a mature gemma, 

 magn. 550 times, formed of one cell-layer at the margin and 

 several in the centre. 



Fig. 126. Tftrnphis felliicidn. A shows a gemma /• 

 with the stalk broken off at a ; a marginal cell of the 

 gemma has grown out into the protonema-filament x y". 

 from which the expansion p has been formed as a lateral 

 shoot, and has sent out the rhizoids 7f, iu', lu". J> a flat 

 pro.embrj-0 p, from the base of which a leaf-bud A' and 

 root-hairs w, -u' have proceeded ; the base of the pro- 

 embryo often puts out a number of new flat pro-embryos 

 before it proceeds to form a leaf-bud. A magn. 100 times. 



viurah's, Grimmia piilvinata, Ftmaria hygrometrica, Trichostomwn rigidum, Airichiivi. 

 But aerial rhizoids also can produce both a protonema with chlorophyll in their cells 

 and leaf-buds directly ; and Schimper adduces the remarkable fact, that annual male 

 plants are produced in this way in the perennial patches of the female plants of 

 Dicranum undulatuin, and effect their fertilisation. 



Even the leaves of many Mosses produce a protonema, simply by their cells 

 growing out into tubes which then become segmented, as happens in Orthotrichtim 

 LyeUii and O. ohtusifoUtim ; in 0. phyllanthuin penicillate tufts of club-shaped pro- 



