ACROGENS, OR FLOWERLESS PLANTS. 



71 



whorls of minute flat leaves ; and the theca itself to be the 

 excavated distended apex of the stalk, the cellular substance 

 of which separates in the form of sporules. 



604. There are also in mosses certain organs, called anthers 

 by some, which do not appear analogous to the male appa- 

 ratus of flowering plants, and the nature of which has not 

 been demonstrated. They are jointed filaments, staminidia or 

 antheridia, containing vibrios lodged in mucous cells, and sur- 

 round the rudiment of the future theca. 



At figure 315 the flask-like figure is a young sporangium, or in this state pis- 

 tillidium ; and the club-shaped body on its left, a staminidium. The articu- 

 lated threads may be abortive staminidia. 



605. LICHENS are cellular expansions, usually horizontal, 

 but occasionally perpendicular, consisting of a tkallus 331 , or 

 combination of stem and leaves, upon which shields, apotliecia, 

 or reproductive organs, appear 331 . 



606. The shields consist of a margin, enclosing a kernel, 

 nucleus, in which tubes containing sporules, and called asci, 

 are imbedded. 



They vary a little in nature, whence they have received the following other names : 

 scutellum 337 ; orbilla, which is the same thing ;pelta 339 ; tuberadum 335 ; tricaor 

 gyroma ; if covered with sinuous concentric furrows, lirella 333 ; patellula 334 . Be- 



sides the foregoing, some other peculiar terms are used by writers on Lichens. 

 Asci are tubes of the nucleus, containing sporules ; the latter are sometimes 

 named gongyli : periikedum is the part in which asci care immersed ; hypothe- 

 cium is a substance overlying the pcrilluvinin. J'oi/ctiu are stalk-like elonga- 

 tions of the thallus 339 ; scypha or oplarium is a cup-like expansion of a 



