CHYTRIDIALES 465 



(1948c: 509), from water and soil containing animal and vegetable 

 debris, Karling (1949c: 299), saprophytic on vegetable debris, Sparrow 

 (1952d: 768), United States; saprophytic in Elodea canadensis, grass, 

 Sparrow (1936a: 453), plant debris, Richards (1956:263), Great Brit- 

 ain, Typha leaves, Scherffel (in Domjan, 1936), Hungary; decaying 

 vegetable debris, Sparrow (1952a: 39), Cuba; Shanor (1944:331), 

 Mexico; Karling (1945a: 35), Brazil. 



This is a ubiquitous chytrid and rare are the submerged decayed 

 bits of the softer parts of phanerogams which do not contain it. The 

 species is readily distinguished from the less common Cladochytrium 

 tenue by the brilliantly colored globule of the zoospore. This coloration 

 makes its appearance early in the development of the sporangium. 



Observations by Karling and later ones by Sparrow on what appears 

 morphologically to be Cladochytrium replicatum indicate that it is 

 primarily saprophytic. The fungus was grown on maize-meal agar by 

 Sparrow (1931c), but it could not be freed from bacterial contamination. 

 Material of it was later cultivated by Karling (1935), Couch (1939a) 

 and others not only on maize-meal agar but also on prune, malt, 

 potato-dextrose, and mannite-soil agars. Karling found that sporangia 

 formed only in liquid media. Of the agars used, maize meal and mannite 

 soil were most favorable. 



In spite of the amount of study accorded Cladochytrium replicatum 

 certain aspects of it still need clarification. Primarily, these center around 

 the nature of the resting spore. Such structures were not observed in the 

 original isolate. In a strain (supposedly of this species but termed C. 

 nowakowskii) parasitic on algae, the single resting spore observed 

 (Sparrow, 1931c) was essentially smooth- walled. In another, a sapro- 

 phytic strain studied by Sparrow (1933a), the resting spores were 

 unquestionably spiny. Karling (1935) described the wall as predomi- 

 nantly smooth, even though spiny ones were present "in a large number 

 of sporangia." He was, incidently, unable to induce his strain to infect 

 living algae. The fungus cytologically investigated by Karling (1937b), 

 see "Cytology," page 87, produced both smooth and spiny-walled 

 resting spores, and in another isolate he reported (1941b: 108) that only 

 10 per cent of the resting spores were smooth, the great majority being 

 spiny. Since none of these studies was made from single-spore isolates, 



