CANNON: GERMINATION OF PHORADENDRON 441 
cylinder, the hard bast, as well as the suberized cork cell-walls 
were colored yellowish, the reaction for corky and for lignified 
tissue. And it was observed that the cell-walls of the host adja- 
cent to the upper two thirds of the haustorium reacted to the test 
for suberized walls, and these were the cells which were seen to 
be compressed in a direction parallel to the surface of the haus- 
torium, and which probably 
somewhat earlier had been 
moistened with the secre- 
tions of the haustorium. 
Naturally the cells nearer 
the tip of the haustorium, 
whose walls were of cellu- 
lose, gave no indications of 
pressure. It appears prob- 
able, therefore, that the en- 
trance was made by press- 
ing the loosely constructed 
tissue of the lenticel to one a 
side, and afterwards, when FicurE 4. P_villosum onash. The haus- 
the deeper cortical cells torium is making its way between the hard bast 
of the cortex, but does not dissolve them. , 
whose walls were of cel- mistletoe ; cam, cambium. 
lulose were reached, the 
solvents secreted by the haustorium became for the first time of 
service to the growing root by making the resistance of the host 
less, as well as by preparing the host-tissues for absorption. 
The general forms of haustoria which have penetrated in the 
manner above outlined, and on this host, as compared with those 
of the haustoria on the mesquite, point also to this conclusion. 
In the former the haustoria are most frequently wedge-shaped, in 
the latter they may be more or less spread out and brush-formed 
(FIGURE 4) and in the latter also there were no evidences of pres- 
sure exerted by the mistletoe qn the host’s tissues. 
Penetration in the other species, it can thus be seen, takes. 
place in quite another manner. This presumably, in part at least, 
is due to the differences in the structure of the branch of the two 
hosts. The axillary buds of the mesquite are closely enwrapped 
by protecting scales, and the internodal portions of the branch are 
