XI 



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

 his which enter the substratum. 



Secondary thalli, 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 hyphal 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 ( Caliciaccae 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, GvropJiora), 



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 sur le thallus 

 clu lichen Peltigera aphthosa Hoff. Bull. 1' Acad. Imp. Sc. St. Petersb. 



24 : 54 8 -559- l8 7 8 - 



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

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



3. BACHMANN, E. Der Thallus der Kalkflechten. Ber. deutsch. hot. 

 Ges. 10 : 30-37. 1892. 



