1918} W EIR—RAZOUMOFSKYA 27 
Montana. The parasite in this case caused unusually large and 
elongated swellings on the main stem of young trees, but the 
plants apparently were never able to come to maturity, remain- 
ing about 5-8 mm. high. One of the pines was transplanted into 
the greenhouse, and the context of the swelling shriveled up in a 
manner indicating that it was composed of very spongy tissues. 
The tree, however, remained living. The fact that 220 seeds of 
R. americana were sown on 6 different species of white pines with 
no result except the germination of the seeds further supports this 
observation. The trees tested were Pinus Lambertiana, P. monti- 
cola, P. Strobus, P. edulis, P. cembroides, and P. Cembra. R. ameri- 
cana is reported by CouLTER and NEtson® on Pinus flexilis. The 
results of sowings on Larix europea, L. occidentalis, Picea sitchensis, 
P. Engelmanni, P. excelsea, Abies nobilis, A. lasiocarpa, A. grandis, 
Tsuga heterophylla, Pseudotsuga taxifolia, Thuja plicata, Taxus 
brevifolia, Populus trichocarpa, Betula occidentalis, and Alnus 
tenuifolia were negative. 
SUMMARY.—The hosts of Razoumofskya americana are Pinus 
_ Contoria, P. Banksiana, P. attenuata, P. Jeffreyi, P. montana, 
P. ponderosa, P. flexilis, and with difficulty P. albicaulis. The 
plant is of economic importance so far as known only on the two | 
first named species. Morphological changes are induced by change 
of host or condition of growth, but not to an extent that this, the 
most characteristic of all members of the genus on pines, could be 
confused. 
Cultures with hemlock mistletoe 
In the St. Joe National Forest, Idaho, are several areas of almost 
pure stands of Tsuga heterophylla heavily infected with R. isugensis 
(figs. 18, 19). In the border zones of these areas a form of mistle- 
toe has been collected on Abies grandis and A. lasiocarpa which 
varies in a number of details from the form collected on the same 
hosts in regions where the large mistletoe on Pinus ponderosa 
occurs. In order to see whether this is a case of R. tsugensis infect- 
ing other hosts than the common western hemlock, and also to 
determine its host range in general, the cultures given in table VI 
were made. 
§ New Manual of Botany of the Rocky Mountains. 146. 1909. 
