BE rt age ee 
CANNON: GERMINATION OF PHORADENDRON 443 
Although the method of securing an entrance into the hosts 
is in the two species of mistletoe and the two kinds of host plants 
above considered unlike in certain particulars, they agree in this, 
namely, that the solvents secreted by the haustoria of the parasite 
do not in either case dissolve suberized cell-walls, and apparently 
cannot doso. For this reason the points of admission open to the 
mistletoe are determined solely by the character of the host-sub- 
stratum, whether its cells are loosely put together, as in the lenti- 
cels of the cottonwood, or the place where the parasite seeks ad- 
mission has cellulose cell-walls. 
Finally, it should be stated that the above conclusion is based 
on anatomical evidence alone, and that the subject should be taken 
up from the experimental standpoint before the conclusion can be 
definitely accepted as valid. And this experimental work I hope 
sooner or later to undertake. 
DESERT BOTANICAL LABORATORY, 
Tucson, ARIZONA. 
