68 



LECTURE V. 



lateral outgrowths, not only roots but also the proper shoots of the Moss, which m 

 their turn are the bearers of the sexual organs; the protonema may thus be looked 

 upon as a simple preliminary stage of the whole vegetative body of the Moss. Ihe 

 le^f-like plates of tissue, abounding in chlorophyll, which sometimes occur on the 



Fig. 63,— i^««a>*:« kygromeirica. A germinating spores ; V vacuole ; w root ; s exosporium : B part of a 

 developed protoneroa, about three weeks after germination ; h a prostrate main shoot, with brown walls and oblique 

 septa, from which erect branches proceed j .ST rudiment of a leaf shoot, with root lo (^ X 55° ; ^S X about 90). 



protonema, but which cannot be regarded as leaves in the narrower sense of the 

 word {Teir aphis), also deserve special mention. Like nunierous similar structures 

 in the Algae, Liverworts, and even the prothallia of the Ferns, we have here to do 

 with shoot-formations which, like the cladodes of vascular plants, serve essentially 



FIG. 64. — Protonematous outgrowth from the root of Maiufn harnHtn, with leaf-forming buds AT. luiv the 

 roots of an inverted sod, from which the protonema filaments (;: »} shoot forth (X90). 



only the purpose of presenting a larger quantity of chlorophyll to the light, and so 

 aid nutrition. 



In some subdivisions of the Liverworts we meet with flat broad shoot-axes, 

 which, provided with rhizoids on their under sides, either possess leaf-like mem- 

 branes or entirely dispense with them : this, however, from our point of view, does 



