367 
Physiology of the Saprolegniaceae. 
Also, haemoglobin and *i percent, potassium phosphate and -i percent, 
sodium chloride ; result as in the preceding, except more marked ; about 
75 per cent, of the oogonia have profuse antheridial filaments. 
(d) Haemoglobin and -i per cent, calcium nitrate. Oogonia very 
abundant, with well-developed oospores ; hypogynous cell always present, 
rarely a second cell ; about I per cent, with short antheridial branches. 
(e) Haemoglobin and -i per cent, potassium nitrate. Oogonia abundant, 
oospheres often poorly developed where the antheridial filaments are pro- 
fuse ; antheridial side-branch at times normally developed, with a well-formed 
antheridium. 
(/) Haemoglobin and -05 per cent, calcium phosphate. Oogonia 
abundant, but rather small, with only 1-5 oospores ; hypogynous cell always 
present, rarely a second one ; only 1 per cent, have short antheridial branches, 
with, however, no antheridia. 
(g) Haemoglobin and -i per cent, potassium sulphate. Oogonia 
moderately abundant with well-formed oospores ; hypogynous cell always 
present, rarely a second ; only 1 per cent, with short antheridial branches. 
The rubidium allowed only vegetative growth, which was moderately 
luxuriant. In the ammonium tartrate solution the oogonia were developed 
poorly. 
For a special study of the effects of calcium and potassium sulphate, the 
following sets of cultures were made : — 
(c) -05 per cent, haemoglobin, -i per cent, potassium phosphate, and 
•1 per cent, potassium sulphate. Oogonia fairly abundant, always with 
an hypogynous cell, and always with an antheridial side-branch which bears 
antheridia ; often these antheridia are diclinous and surround the oogonia 
profusely. 
(d) *05 per cent, haemoglobin and -i per cent, calcium nitrate. Oogonia 
abundant with well-formed numerous oospores up to twenty in number ; 
hypogynous cell either present or absent ; antheridial side-branches few, 
short, and undeveloped. 
(/) *05 per cent, haemoglobin, -05 per cent, monohydrogen calcium 
phosphate. Oogonia moderately numerous, from 1-15 oospores, oftener 
only a few ; hypogynous cell with or without a side-branch, which, however, 
is never fully developed. 
(h) -05 per cent, haemoglobin, *i per cent, disodium hydrogen phos- 
phate, and -i per cent, potassium sulphate. Oogonia medium numerous, 
with hypogynous cells ; antheridial side-branches are present, and diclinous 
filaments with antheridia surround the oogonia as in (c). 
H. Saprolegnia mixta , De Bary. This is apparently a form of the 
plant described by De Bary, differing in fly cultures mainly in having 
antheridia on 75 per cent, or more of its oogonia. A full description of the 
plant as it appeared in fly culture is herewith given. 
