i8 
Journal of Agricultural Research voi. xxm, no. i 
combination, a modification of a stain used by E. G. Arzberger, of the 
Office of Agricultural Technology, Bureau of Plant Industry. This 
consisted of applying with a dropper strong acid fuchsin in 95 per cent 
alcohol followed by dipping in absolute alcohol till the excess is washed 
away. Then a saturated solution of Lichtgriin in clove oil is applied. 
This acts as both a clearing agent and a stain. It removes -the red 
from the host tissue, except lignified tissue such as is found in the 
fibrovascular rings, replacing the red by light green. The gradual 
differentiation here can well be observed under the microscope. The 
clove oil is removed with xylol, and balsam is then applied as usual for 
making the mount permanent. The duration of the stain is not known 
to the writer, but mounts several months old are still good. 
TAXONOMY OF THE FUNGUS 
There are so many characters common to all the described species of 
Phytophthora that it is necessary carefully to consider each of them 
before undertaking to determine the proper taxonomic position of a new 
strain. In this case all but one were eliminated by some definite morpho¬ 
logical differences. It was thought well, however, to take into con¬ 
sideration to some extent as well the reactions to different culture media 
and to different hosts. In the writer's opinion the effect on the starchy 
roots, tubers, and fruits of certain plants may prove, after more exten¬ 
sive trial, to be very helpful in delimiting species. 
No effort will be made here to point out a multitude of differences in 
any particular case between the rhubarb Phytophthora and the one 
with which it is compared. It is considered necessary only to give the 
briefest possible consideration to each case, pointing out one or two 
clear-cut differences that will suffice to distinguish them. 
Phytophthora fagi (Hartig) Hartig, P. cactorum (Lebert and Cohn) 
Schrot., P. syringae (Klebh.) Klebh., and P. nicotianae Van Breda de Haan, 
as listed by G. W. Wilson ( 30 ), can all be set aside on the start as having 
the paragynous rather than the amphigynous (17, p. 12J) antheridia. 
In this class also would fall P. jatrophae Jensen and P. faberi Maub. 
(P. theobromae Colem.) (7) at least tentatively, for the sexual phases of 
this fungus do not appear to be perfectly understood. Other morpho¬ 
logical characters, however, clearly differentiate the species from ours. 
Here also should be included P. omnivor a De Bary, for several of the 
fungi that were included under this name are in this respect like the 
others mentioned, although Wilson (30, p. 80) states that “ as P. omnivora 
De Bary is here recognized as an aggregate of undetermined affinity, 
it need be considered no further.” Here, too, would fall Beach’s rhubarb 
Phytophthora (2), a culture of which was kindly furnished the writer. 
In the culture, oospores were found with the antheridium distinctly 
attached at the side of the oogonial pedicel, as with P. cactorum (Cohn 
and Lebert) Schrot. rather than surrounding it. Other cultural char¬ 
acters which will undoubtedly be brought out later by its discoverer 
distinguish his organism unmistakably from that of the present writer. 
Phytophthora palmivora (Butl.) Butl. (3, 4) differs morphologically 
and physiologically from the writer’s species. 
There is left, then, the list given by Pethybridge and Lafferty (rp, 
p. 497) in their paper on Phytophthora cryptogea Pethyb. and Laf., all hav¬ 
ing the amphigynous antheridia, as does the species under consideration, 
which adds one more to the growing list of species with this character. 
