136 THE SAPROLEGNTACEAE 



hence subcylindrical, often bending and partly separating at the joints, 

 soon forming spores which escape as in Achlya by a papilla of variable 

 length. Oogonia borne on short lateral stalks from the main hyphae, 

 rarely terminal on the latter, smooth, spherical, very regular in size, 

 50-6511, most about 6o;j., the rare terminal ones up to gofx thick; wall 

 rather thin, not pitted except under the antheridia, distinctly yellow- 

 brown. Eggs few, 2-5, in large oogonia about 6 or 8, in diameter 24- 

 33[jL, most about 28-30'ii, when nearly mature with several oil drops on 

 one side, then usually with a single, lateral, conspicuous drop at full 

 maturity (but mature oogonia not rarely still contain several or a good 

 many oil drops). Antheridia on all oogonia, usually cylindrical and 

 partly wrapped about the oogonia, diclinous, borne on sparingly branched 

 threads of moderate length from main hyphae or on long threads which 

 terminate more slender hyphae; antheridial tubes obvious and visible 

 for a long time. 



This remarkable plant has appeared but twice. It was found in 

 a collection from a branch (Meeting of the Waters, No. 5, of February 16, 

 192 1 ) where the water is somewhat contaminated by a sewer which enters 

 about a half mile farther up. Pure cultures were made and are being 

 continued. Leptomitus and Achlya oblongata were found at the same place. 

 It was found again near Hartsville, S. C, August 30, 1922. In the behavior 

 of the sporangia and spores the species is exactly intermediate between 

 Achlya and Thraustotheca, or rather it combines in this respect the characters 

 of both. The eggs are, however, more like the latter genus, the eggs 

 having several conspicuous lateral droplets up to a late stage as in T. clavata 

 and differing thus from the eccentric-egged Achlyas. Our figures do not 

 show extreme condition of the late stage, in which the protoplasm draws 

 away from the droplet as much as in ^ . Orion. The antheridial branches also 

 remind one of those of T. clavata and, as in it, are always diclinous. The 

 distinctly brown oogonial wall is also different from any Achlya with 

 eccentric eggs. In such ways this seems nearer Thraustotheca than 

 Achlya, but for ^'arious reasons we prefer to put the species in Achlya 

 at present. The strongest reason is that as our cultures have gone on 

 the Tkraustotheca-Vxke sporangia have grown fewer in proportion. 



The majority of the Thraiistotheca-like sporangia have the peculiar 

 habit of cutting off a considerable area at the tip which does not form 

 spores but contains much less dense protoplasm which usually goes to 

 pieces but may become condensed into a ball. Other parts of the spor- 

 angium, particularly the basal part, may also fail to form spores, the 

 protoplasm remaining undivided or imperfectly segmented into large 

 masses. Even when the spores are discharged at the tips larger masses 

 may be mixed with the normal spores, as is not rare in other water molds. 

 (See Achlya imperfecta.) The sporangial wall may begin its disorgani- 

 zation at any point, but this usually shows first on one side near the cen- 



