EXPLANATION OF TERMS. 



501 



Theca. Same as ascus. 



Thecaspore. Same as ascospore. 



Thermotropism. Phenomena induced 

 in a growing organ by the influence of 

 conditions of temperature. 



Thrush. Disease of the mucous membrane 

 of mouth,throat andoesophagus in children 

 characterised by formation of pustules 

 due to Saccharomyces albicans, Reess. 

 Same as aphthae. 



Tinea tonsurans. Same as ringworm. 



Torulose. Swollen at intervals. 



Trama. In Basidiomycetes : middle tissue 

 in the projections or septa of the sporo- 

 phore which bear hymenium. Same as 

 dissepiment, intralamellar tissue. 



Tremelloid. Resembling Tremella. 



Trichogyne. Thread-like receptive portion 

 developed as part of an archicarp. 



Trophoplast. Same as plastid. 



Trophotropism. Phenomena induced in 

 a growing organ by the influence of the 

 chemical nature of its environment. 



Tube-germination (Sehlauchkeimung). 

 Germination of a spore in which the first 

 product is a germ-tube. Comp. sprout- 

 germination. 



Tubulus. (a) In Pyrenomycetes : Same as 

 neck. (b) In Hymenomycetes : tube 

 lined with hymenium on the surface of a 

 pileus. Same as pore. 



Unicellular. Formed of one cell. 



Uredo. Hymenium producing uredospores 

 only. Termed also uredo-layer. 



Uredogonidium. Same as uredospore. 



Uredospore. In Uredineae : spore formed 

 by acrogenous abjunction on a sterigma 

 from which it separates when mature and 

 on germination produces a mycelium 

 bearing uredospores or uredospores and 

 teleutospores. 



Uterus. In Gastromycetes : same as peri- 

 dium. 



Veil. Same as velum. 



Veines aeriferes. Same as venae in- 

 ternae. 



Veines aquiferes. Same as venae ex- 

 ternae. 



Velum. In Hymenomycetes : special 

 envelope within which the growth of the 

 whole or a portion of the sporophore 

 takes place. Same as veil, involucrum 

 of Persoon. By Persoon applied to what 



is defined above as cortina. See 

 marginal veil, velum universale. 



Velum partiale. Same as marginal 

 veil. See velum. 



Velum universale. In Hymenomycetes 

 sac enclosing the whole of a sporophore 

 as it grows and ultimately ruptured at the 

 apex by the unfolding pileus. Same as 

 volva. See velum. 



Venae externae. In Tuberaceae : white 

 veins seen on section of the sporophore 

 produced by dense tissue containing air 

 and filling the asciferous chambers. 

 Same as veines aeriferes. Comp. 

 venae internae. 



Venae internae. In Tuberaceae : dark- 

 coloured veins seen on section of the 

 sporophore indicating the walls of as- 

 ciferous chambers, which are composed 

 of tissue containing no air. Same as 

 venae lymphaticae, veines aquiferes. 

 Comp. venae externae. 



Venae lymphaticae. Same as venae 

 internae. 



Volva. Same as velum universale. 



Witches' broom. Disease on the silver-fir, 

 birch, cherry, and other trees characterised 

 by the development of a tangle of shoots 

 in a tuft and due to the attack of Peri- 

 dermium elatinum or of Exoascus. 



Woronin's hypha. In Ascomycetes : a 

 coiled hypha found in some forms at the 

 place where the sporocarp subsequently 

 developes and probably homologous with 

 an archicarp. 



Xyloma. Sclerotioid body of varying 

 shape which does not send out branches 

 developing into sporophores but produces 

 sporogenous structures in its interior. 



Yeast-fungus. Species of Saccharomyces. 

 Sometimes used as equivalent to the 

 growth form distinguished as Sprouting 

 Fungus, but this misuse leads to con- 

 fusion. 



Zoogloea. In Schizomycetes : colony 

 imbedded in a gelatinous substance. 



Zoospore. Motile spore. 



Zygospore. Immediate product of conju- 

 gation of two similar gametes. 



Zygosporophore. In Mucorini : same as 

 suspensor. 



