62 THE SAPROLEGNIACEAE 



in Flora, we shall not here describe these five forms further than is done 

 in the following key (the plate references are omitted): 



Antheridial cell very rarely cut off, but more or less thread-like projections enter the oogonia 

 from below. Stalks of oogonia much bent. Pits small, numerous and conspicuous. 

 Eggs mostly 3-6, rarely 12-20; diameter 20-30;!.. Germination period 70-80 days 



Var. I 

 Antheridial cells rarely absent under the oogonia. 



Pits numerous. Germination period of eggs 70-80 days. 

 Antheridial cells very rarely absent: under these usually still other cells cut off. Eggs 



2 to over 30; diameter 18-22. sjx Var. II 



Antheridial cells always present, but no other cells cut off beneath them. Not rarely 

 are formed lateral outgrowths from the hypogynous cell, which lay themselves 

 against the oogonia, and appear like androgynous antheridia. Eggs i to over 



40, diameter 15-2511 Var. Ill 



Pits fewer, not over 4. Germination period 39-50 days. Diameter of eggs i8-23[x. 

 Wall of oogonium very thin, by slight pressure becoming flattened. No extra cells 

 beneath the antheridial cell. Eggs often polygonal from pressure, mostly 2-10, 



but up to 35-50 in an oogonium Var. IV 



Wall of oogonium stronger; additional cells cut off under the antheridial cell. Antheri- 

 dial tubes 1-2, very long, bent, often filled with plasma. "Starker als bei irgend 

 einer der anderen" varieties. Eggs mostly 3-12, never more than 12. 



Var. V 



Saprolegnia intermedia (Form 6 above) is said by Alaurizio to be 

 nearest his Var. V, which agrees in the almost constant presence of the 

 antheridial cell, the well developed antheridial tubes with thin walls 

 and abundant protoplasm, and in the small number of pits. In the 

 thin wall, few pits and number of eggs, he says it approaches his Var. IV. 

 This sixth form (5. intermedia) may be briefly defined thus: 



Antheridial cell almost always present; antheridial tubes usually 

 well developed, single or several, simple or branched, thin-walled, with 

 distinct protoplasmic contents, oogonia in groups on short or long stalks, 

 or in chains or intercalary, spherical or pear- or barrel-shaped; mem- 

 brane thin, colorless, in small oogonia without pits, in larger ones with 

 2-5 pits, which are not easily seen except with high power. Eggs 6-10, 

 or up to 40 in large oogonia; diameter 19-2311. Germination period 

 20 days. 



Saprolegnia hypogyna var. Coregoni Maurizio. Mitt. d. Deutsch. 

 Fischerei-Vereins 7: 55. 1899 (Form 7 above). On account of the in- 

 accessibility of the original, we give below a practically complete trans- 

 lation of Maurizio's description (there are no figures) : 



" Isolated from an egg of Coregonus [pike] which came from a fish 

 hatchery on the Hallwylersee, Kt. Aargau. Cultivated for over a year. 

 Turf up to I cm. long. Sporangia as usual. Oogonia intercalary in 

 chains, or in sympodial arrangement, or finally rather rarely in racemes. 

 Stalk of moderate length and frequently remarkably slender; when 



