ACHLYA 127 



14. Achlya apiculata \ ar. prolifica Cokcr and Coiicli n. \ar. 



Plates 4;, and 50 



Growth fairly dense hut only moderately long, reaching a length of 

 0.3-0.4 cm. (on termite ants or mushroom grubs). Main hyphae branch- 

 ing considcral)ly, rarch up to 90;x close to base; the tips of hyphae pointed 

 and hyaline when young, ilrying or becoming rounded with maturity. 

 In summer (room temperature of 21-32.5° C.) the ends of the hyphae 

 become elaborately branched and the tips considerably swollen. Spor- 

 angia, spores and gemmae as in .4. apiculata, but the gemmae less num- 

 erous. Oogonia produced in all cultures, at low temperature (12-20° C.) 

 in great abundance, but at room temperature (21-30° C.) usually few 

 and sometimes none; diameter 40-90!x, in most 55-65JJ., spherical, less 

 often oblong or rarely cylindrical in old sporangia as in Saprolegiiia 

 ferax, quite often provided with a short apiculus, rarely with a long one. 

 Walls smooth and unpitted except where the antheridia touch ; hoAvever, 

 in old cultures on corn grain the wall may be considerably roughened 

 but not typically pitted (pi. 43, fig. 7). Oogonial stalks as in /I. apiculata 

 except more branched. Eggs usually i or 2, rarely as many as 5 ; antherid- 

 ial branches, antheridia and the structure of the egg the same as in the 

 species. 



This plant appeared once (No. 2 of February 28, 1921, in branch in 

 Latta's Woods) among more than 300 collections made around Charlotte 

 N. C. by J. X. Couch. 



The present \ariety in vegetative growth and in the shape and size 

 of the sporangia and spores is indistinguishable from the species. The 

 oogonial stalks of both plants are quite similar, though the stalks of the 

 variety show a stronger tendency to branch than in the species. Apic- 

 ulate oogonia are found in both plants but oogonia with such outgrowths 

 are more abundant in the variety. The outstanding differences between 

 the two plants are found, first, in the regularity with which our present 

 plant bears sexual fruits even in room temperature (17-24° C), while A. 

 apicnlat-a fruits \-ery poorly in the laboratory; second, in the relati\-e 

 number of oogonia produced under the optimum temperature for both 

 plants, the number being about five times greater in the variety than in 

 A. apiculata; third, in the comparati%'e size of the oogonia, the average 

 diameter in the \ariet>- being between 55 and 65;jl while in the species the 

 average diameter is between 70 and 8o;j.; and fourth, in the relati\e nu mber 

 of eggs in the oogonia, the usual number in the variety being i or 2, rarel\- 

 5, while in A. apiculata the usual number is between 3 and 5, rarely 10. 

 This \ariety is the only member of the Saprolegniaceae in which we have 

 been able to observe sprouting eggs. Old eggs from a culture made August 

 15, 1921, were put on corn meal agar in February, 1922. In forty-eight 

 hours they had sprouted to form long, branched threads. 



