128 THE SAPROLEGNIACEAE 



The following experiments are typical of many made to determine 



the effects of temperature on the production of sexual organs. 



On termite ants in sterile well water in ice box. Temperature ranging from 12° C. to 20° C. 

 Growth good, 5 cm. long. A good many sporangia formed and emptied, and a good 

 many oogonia, some of them in empty sporangia as in several previous cultures 

 on ants in ice box. Oogonia with very long stalks. 



On termite ants in sterile well water in room. Temperature ranging from 17 -22 C. Growth 

 good, the ends of hyphae considerably branched, swollen and contorted; many spor- 

 angia and a fair number of oogonia. 



On termite ants in sterile well water in room. Temperature ranging from 21° to 32.5° C. 

 Growth very poor, bacteria bad. Two days later dead. 



On piece of boiled corn grain in sterile well water in ice box. Temperature from 12 -20 

 C. Growth very good, mycelium dense, threads much branched and curled. Many 

 sporangia, a large number of which had emptied; very many oogonia close to periphery 

 of mycelium, oogonial stalks much curled and branched as also the antheridial stalks. 

 Oogonia average by count about five times as many in a given field as in the species. 



Onpieceof boiled corn grain in sterile well water in room. Temperature 17 — 22°C. Growth 

 good, the ends of hyphae considerably branched, swollen and contorted ; many sporangia, 

 and a fair number of oogonia. 



On piece of boiled corn grain in sterile well water in room. Temperature 21 -32.5 C. 

 Growth good, but soon mterfered with a. id killed by bacteria. 



15. Achlya megasperma Humphrey. Trans. Amer. Phil. Soc. 17: 118. 

 pi. 18, figs. 74-77. 1892 [1893]. 



Plate 44 



Mycelium slenderer than in most Achlyas. Sporangia very abundant, 

 of the typical Achlya type, borne singly or in clusters (often as many 

 as eight) on the ends of hyphae, varying much in shape from the long, 

 slender, tapering sporangia of Achlya apiciilata to a club-shaped form 

 swollen at the distal end; loo-ioootj. long, most between 300 and 400[j,. 

 Spores ii'i. in diameter. Gemmae developed in considerable abundance, 

 either single and shaped like a sporangium with pointed tip or very 

 elaborately branched ; when solitary often separating from the hypha and 

 falling to the bottom. Oogonia racemosely borne on branches which are 

 about as long as or shorter than the thickness of the oogonia; rarely the 

 oogonial branches may be longer. Oogonia without an apiculus, usually 

 spherical, occasionally oblong, rarely cylindrical, 60-119;;. thick, usually 

 between 70 and 8o;j., oogonial wall thickened and without pits except 

 for thin places under the antheridia. Eggs i-io or rarely more, usually 

 2-5, almost or entirely filling the oogonium, often elliptic from pressure; 

 39-66tJ. thick, usually between 42 and 52[ji, (in an oogonium in which there 

 were 9 eggs the average size was 44.I1J.) ; structure subcentric and exactly 

 as in A. apiculata; walls 3-4. 6[i thick. Antheridial branches diclinous 

 or androgynous but never arising from the oogonial stalk, usually di- 

 clinous, often much branched and not applied to oogonia; long and very 

 slender, becoming barely visible after the eggs are formed. Antheridia 

 tuberous and fairly conspicuous; usually one or two on each oogonium; 

 not rarely absent. 



