FAMILY CREXOTHRICHACEAE 



987 



FAMILY II. CRENOTHRICHACEAE HANSGIRG.* 

 (Osterr. Bot. Ztschr., 36, 1888, 228.) 



Filaments not branched, attached to a firm substrate, showing differentiation of 

 base and tip. Sheaths plainly visible, thin and colorless at the tip, thick and en- 

 crusted with iron at the base. Cells cylindrical to spherical, dividing in three planes 

 to produce the spherical non-motile conidia. 



Genus I. Crenothrix Colin. 



(Cohn, Beitr. z. Biol. d. Pflanz., 1, Heft 1, 1870, 108; Phragmidiothrix Engler, 

 Verh. Bot. Ver. Brandenb., 24, 1882, 19.) From Greek crenos, spring and Ihrix, hair. 

 Characters as for the family. 

 The type species is Crenothrix polyspora Cohn. 



1. Crenothiix polyspora Cohn. (Beitr. 

 z. Biol. d. Pflanz., 1, Heft 1, 1870, 108; 

 Hypheothrix kuehmana Rnbenhorst, 

 Flora europ. algarum, Sect. II, 88; Lep- 

 tothrix kuehniatia Rabenhorst, Algen 

 Sachsens, No. 284; Crenothrix k^iehniana 

 Zopf, Zur Morphologic der Spaltpilzen, 

 1882, 36; Crenothrix vianganifera Jack- 

 son, Hyg. Rund., U, 1904, 19.) From 

 Greek, many spores. 



Long, articulated filaments, un- 

 branched, enclosed in a sheath which 

 becomes expanded toward the tip. The 

 sheath is composed of organic matter 

 encrusted with iron. Filaments, in- 

 cluding the sheath, measure 2 to 9 mi- 

 crons in diameter. 



Vegetative cells vary markedly in 

 length from long cylindrical to short 

 ovoid forms. 



Conidia, spherical, 1 to 2 microns in 

 diameter, are liberated from the ex- 

 panded tips of the sheaths. Thej- are 

 non-motile. 



Cultivation : Has not been grown on 

 artificial media in pure culture. 



Conidia may germinate upon the ex- 



terior of the sheath from which they 

 have been liberated, giving rise to new 

 filaments attached to the surface of the 

 older one, presenting a simulation of 

 false branching. 



Cholodny believed Clonothrix fusca 

 to be identical with Crenothrix poly- 

 spora. However, Clonothrix fusca s]\ov,'S 

 genuine false branching and produces 

 conidia bj^ fission in onlj^ one plane, so 

 that the filaments taper toward the tip 

 instead of expanding (see Kolk, Amer. 

 Jour. Bot., 2S, 1938, 11) for a clear cut 

 differentiation of these two species. 



Source : This organism is wide-spread 

 in water pipes, drain pipes and springs 

 where the water contains iron. It fre- 

 quentl}' fills pipes under such circum- 

 stances and causes a real nuisance. 

 Found by Cohn in samples of water from 

 springs in the neighborhood of Breslau, 

 Germany. 



Habitat: In stagnant and running 

 waters containing organic matter and 

 iron salts, growing as thick brownish or 

 greenish masses. 



* Completely revised by Prof. A. T. Henrici, University of Minnesota, Minneap- 

 olis, Minnesota, December, 1938; further revision by Prof. Robert S. Breed, New 

 York State Experiment Station, Geneva, New York, Julj, 1946. 



