Rhizoids, special hyphal elongations from the under surface of the thal- 

 lus which enter the substratum. 



Secondary tlialli, thalloid outgrowths from the thallus and podetia of 

 lichens. Sometimes also applied to the podetia of Cladonia. 



Seta (Setae), see Fibril. 



Soredium (Soredia), a minute spherical body consisting of algae en- 

 closed by a hvphal network and having the power of developing into a new 

 lichen. 



Spermagonium (Spermagonia) , the structure upon the thallus con- 

 taining the so-called sterigmata and spermatia. 



Spermatium (Spermatia), a spore-like body formed in the sperma- 

 gonium. (Considered by Stahl and others as the male reproductive organ 

 of lichens.) 



Spore=sac, the closed sac-like structure in which the spores are formed. 



Squamule, a small entire thalloid lobe. Usually forming the transition 

 to the typical foliose thallus. 



Sterigmata, the filaments of the spermagonium bearing the spermatia. 



Stipe, an apothecial stalk free from algae ( Caliciaceae and Baeomyces). 



Symbiosis, a contiguous association of two or more organisms ac- 

 companied by an interchange of assimilated food-substances. 



Thallus (Thalli), the vegetative and assimulative portion of lichens, 

 bearing the apothecia and soredia. 



Theca (Thecae) , see Spore-sac. 



Thecium (Thecia), the layer consisting of thecae and paraphyses. 



Umbilicus, the single root-like attachment of certain lichen-thalli ( Um- 

 bilicaria, Gvropkora). 



Verrucose, see Warty. 



Warty, referring to a thallus bearing numerous thalloid elevations 

 larger than the granules. 



LITERATURE. 



The references here given are to the principal works on the mor- 

 phology, physiology and chemistry of lichens issued since the year 

 1850, and terminating with the year 1896. 



1. Babikoff, M. Du developpement des cephalodies sivr le thallus 

 du lichen Peltigera aft/iikosa Hoff. Bull. 1' Acad. Imp. Sc. St. Petersb. 

 24:548-559. 1878. 



2. Bachmann, E. Ueber nichtkrystallisirte Flechtenfarbstoffe. Jahrb. 

 wiss. Bot. 21 : 1-60. 1890. 



3. Bachmanx, E. Der Thallus der Kalkflechten. Ber. deutsch. bot. 

 Ges. 10: 30-37. 1892. 



