374 
Kauffman. — A Contribution to the 
at the time when I needed it, the study has not been made. There appeared, 
on the other hand, a Saprolegnia which I discovered to be X. hypogyna as 
detailed above. As this species seemed to offer as great, if not greater, 
possibilities than even S. ferax, it was decided to study it instead. 
A pure culture was transferred to a sterilized wasp as offering the 
ordinary insect culture-media in general use. As in X. mixta , sporanges 
are formed and emptied in great numbers within a few days and following 
a luxurious growth of hyphae. On the ninth day oogonia were abundant, 
and a few days later very abundant, containing from one to ten oospores. 
In this culture not a single antheridial filament was found, although it was 
diligently sought ; also the hypogynous cell was always present, and all the 
other chief characters of the plant agreed with the description by De Bary 
of 5. hypogyna. If, therefore, Pringsheim and De Bary had the same species 
which I had, and it would seem that they had at least one of the forms, 
then, as long as they used flies or similar substrata, they would be sure to 
find only the hypogynous cell and no antheridial side-branches. 
Now if 5. hypogyna is grown in -05 per cent, haemoglobin solution, its 
appearance is nearly like that on the wasp, except that a very few hypo- 
gynous cells have a short protuberance — an abortive antheridial filament. 
If peptone is added to the haemoglobin solution no protuberances appear 
at all. In haemoglobin solutions Klebs found that K 3 P0 4 , Na 2 HP0 4 , and 
Ca 3 (P0 4 ) 2 were the only salts which induced antheridial formation in 
X. mixta. As noted in another part of this paper, not only these but other 
salts also induced antheridial formation in the case of X. hypogyna. These 
different inorganic salts act with very different degrees of effectiveness ; in 
fact it is possible to select a regularly graded series of cultures showing the 
relative value for antheridial formation of the several salts used. Such a 
series is shown in Plate XXIII. The haemoglobin cannot be sterilized, but 
as the cultures were made in winter and kept continuously at a temperature 
of about 15 0 C., no trouble was experienced in this respect. The haemo- 
globin used (Merck’s) was very clean itself, and if the paper, dishes, &c., 
used in weighing and transferring were sterilized, very seldom did any bac- 
terial contamination appear in the comparatively short time necessary for 
the experiments. The following salts, decreasing in effectiveness for the pro- 
duction of antheridial side-branches, were used: K 3 P0 4 , KN0 3 , Na 2 HP0 4 , 
K 2 S0 4 , (Ca 3 P0 4 ) 2 , and Ca(N0 3 ) 2 , and these were added to a haemoglobin 
solution. It can be seen that X. hypogyna is very well adapted to show off 
the action of the various salts. KN0 3 andK 2 S0 4 were especially favour- 
able and produced antheridial branches on as high as 40 per cent, of the 
oogonia. This result differs somewhat from that of Klebs, and the question 
of impurities in the salts used would naturally arise. It must be remembered, 
however, that minute amounts, such as might be present in the salts used, do 
not affect the production of oogonia and antheridia, at least not to such a 
