440 CANNON: GERMINATION OF PHORADENDRON 
structure of the host. I would not say that the mistletoe does 
not gain entrance in these hosts in any other way, but I have 
seen nothing that would indicate that it does. 
In the case of the ash, the mistletoe seeds, P. vzllosum, falling 
on the younger and smooth branches send out their hypocotyls 
and these attach themselves at once to the substratum. The 
branches are provided with prominent lenticels and if one of these 
chances to be directly beneath a disc, the epidermal cells of the 
disc enter it, dissolving or pushing to one side, or both, the cells 
of the host, and at length find themselves in the cortex. This is © 
not a matter of solution entirely, since the host-cells at the side 
FiGure 3. Secreting cells at the edge of the disc of such a young mistletoe as that 
shown in the preceding figure. The cells are evidently active, but a study of the sec 
tion from which the sketch was made does not show that the host tissues are being 
dissolved as the sketch would indicate. 
of the haustoria give evidence of having been subjected to pres- 
sure by them, and the walls of such cells, as will appear directly, 
are suberized. That-is, as far as I have been able to determine, 
and to express the matter in another way, the cell-walls of the 
host which make up the lenticels and which had been affected by 
the solvent, were not suberized, as is shown by the following tests- 
In the section from which FricuRE 4 was sketched, the walls of the 
host-cells which were immediately in front of the tip of the haus- 
torium, and for a distance back equal to about one third of its 
length, gave the cellulose reaction with iodine and sulphuric acid ; 
they were colored blue, while the lignified portions of the central 
