6 'MANUAL OF BOTANY 



account of their possessing, In addition to those cells which are 

 called parenchymatous, elongated, generally thick-waUed cells. 

 Pig. 6. Fig. 7. 



Fig. 6. The common Mushroom (Agaricus 

 campestris). There are three receptacles 

 (fructificafion), arising from the mycelium, 

 mn, below : one young and nearly globular, 

 and two mature, a. Pileus. 6. LameUse. 

 c. Anuulu.=. 



Fig. 7. A portion of the flat 

 thallus-like stem of Mar- 

 chantia polymorpha, showing 

 an antheridial receptacle, r, 

 supported on a stalk, s. 



called. prosenchymatous cells, ot fibres, and also in most cases vari- 

 FiG. 8. ously formed tubular organs which are 



known under the name of vessels. The dis- 

 tinction is not, however, absolute, as certain 

 of the Algffi afford undoubted instances of 

 the occurrence of vessels kno^\'ii as sieve- 

 tubes, much like forms met with in the 

 highest flowering plants. In the higher 

 Mosses, e.g.Polytrichinn {figs. 9 and 10), 

 the stems often contain elongated cells, 

 which are to a certain extent thickened, 

 and differ little from the true wood-cells 

 met with in the more highly developed 

 plants. Correlated with this greater de- 

 velojjment of the organs of nutrition we 

 find the reproductive apparatus similarly 

 advanced in complexity of structure, as 

 will be hereafter described. 



The Liverworts and Mosses are, how- 

 ever, destitute of vessels, such as exist in 



the next and all the higher groups of plants. 



Fig. 8. Jungermannia 

 hidentttla. The stem is 

 creeping, and bears 

 numerous small imbri- 

 cated leaves. 



