104 
Peirce . — The Dissemination and 
a year old still attached to the leaves on branches which they struck and 
on which they had failed to germinate. The attachment of the ‘ seed 5 is 
then very firm, and may be increasingly firm as time goes on. 
So far as my observation goes, the majority of the ‘seeds’ strike the 
leaves of the pine, either of the tree on which they grew or of one near by. 
Owing to the various positions of the fruits, the directions in which the 
seeds are shot are very various. Some must go to the ground at once, 
others up into the air, but the majority certainly nearly horizontally, for in 
the close clumps of trees where Arceuthobium is most abundant the para- 
sites are, most of them, on branches from four to ten feet from the ground. 
I have never seen the plant high up on old Monterey Pines, though it is 
reported on the high branches of other pines elsewhere. In the Stanford 
Arboretum it is not on the branches at all, but forms, a more or less com- 
plete ring around the trunk of the tree two or three feet from the ground. 
Comparatively few of the enormous number of seeds produced where Arceu - 
thobium flourishes reach places favourable for germination and for penetra- 
tion into a host. The explosive fruit, therefore, is a very powerful but very 
wasteful means of disseminating the plant, much less efficient than the less 
astonishing fleshy fruits of Viscum , Phoradendron , and other Loranthaceae. 
Germination. 
The ‘seeds’ of Arceuthobium occidentale will germinate on anything, 
if they will germinate at all. I have seen germinating seeds on pine- 
needles, dead as well as living, on dead branches, on trees and shrubs of 
other sorts, on a fence board, anywhere where the air was moist and warm 
enough. But I have not been able to grow the plants at Stanford 
University. The reason for this, I am sure, is the cold of winter and the 
drier air. Until the parasite has penetrated into the host it can get water only 
from the air. It is therefore very dependent upon such a degree of moisture 
in the air as will not rob the gelatinous coat of the seed of more water than 
the embryo requires for its growth and penetration into the host. The 
gelatinous coat is the water-reservoir of the embryo as well as the means 
of attaching the seed to the host — two very important functions, requiring 
the differentiated cell-walls above described. Germination will not be 
successful, however, unless the seed fall on a branch, the rough surface or 
the angles of leaves or branches of which oppose the gliding of the growing 
root over the surface. On leaves the root will continue to grow, gliding 
over the surface, to an astonishing length, three centimetres or even more, 
until no longer enough food can be taken out of the endosperm. 
The embryo is a simple cylindrical structure lying in the endosperm at 
the upper end, that is, toward the tip of the fruit. The cotyledons are 
represented only by a slight notch at the lower end. The epidermis is the 
