14 BOTANICAL GAZETTE [JULY 
_ by the parent when growing on what we may term the mother host, 
the limitations of a species are naturally more difficult to define. 
Notwithstanding this change, however, a good species should 
be sufficiently characteristic on any host and under any of the 
ordinary conditions of growth as to be readily recognized by one 
having a wide knowledge of the plant in the field. We do not think 
of the low, scrubby Douglas fir of central Montana as anything 
different from the gigantic form of this tree occurring in the Puget 
Sound region. 
It is of considerable economic importance that R. campylopoda 
will infect Pinus resinosa, P. sylvestris, and P. montana, and may 
be expected to be a serious pest on these trees in localities where 
conditions are favorable. In drier sites of the Lake states and, 
in fact, throughout the Northeast, where it is proposed to plant 
P. resinosa, this mistletoe would undoubtedly grow luxuriantly, 
and care should be exercised against its introduction into these 
regions on nursery stock during the early period of infection. 
Seeds of R. campylopoda were sown on the following pines in 
most cases in the greenhouse, but either due to the poor quality of 
the seed, loss of seed, or low vigor of the trial hosts the results were 
mostly: negative. This does not mean, however, that all of the 
species mentioned here are immune. In a few cases infection did 
occur on species not mentioned in the table, but the results were 
of a nature that it is thought best not to report them at this time. 
These were Pinus Banksiana, P. mayriana, P. Strobus, P. Cembra, 
P. cembroides, P. edulis, P. Lambertiana, and P. monticola. Sowings 
made on Pseudotsuga taxifolia, Larix leptolepis, Tsuga heterophylla, 
Thuja plicata, T. occidentalis, Cupressus arizonica, Picea Engelmannt, 
P. canadensis, Populus tremuloides, P. trichocarpa, Betula occt- 
dentalis, Alnus tenuifolia, Acer glabrum, and Prunus demissa 
resulted negatively. 
SuMMARY.—Results of cultures so far indicate that the mistle- 
toes known under the names Razoumofskya campylopoda and 
R. cryptopoda are distinct. Each form, however, may exhibit con- 
siderable variation, due to geographic location and host. The 
relationship of the two forms will be further considered when a 
number of experiments now being conducted are completed. 
