THE MISTLETOE. 
27 
tured by the pressure from within, and at the same time the seed 
is expelled. Dr. MacDougal thus describes the phenomenon: 
“ One may stand under a pine tree on a quiet morning and hear 
the sharp click accompanying the expulsion of the seeds from the 
berries at irregular intervals. If the branches are jarred or 
shaken, however, the irregular explosions give way to fusillades 
by which nearly all of the berries on a plant will be set in action 
at once. The expulsion of the seed occurs as soon as the berry 
has broken loose from the stalk, and as these berries were origi¬ 
nally in all positions the seeds are sent out in all directions. . . . 
The only part that animals play in the dissemination of the seeds 
would be in causing the discharge of the berries, a matter of no 
direct value, since they are capable of quite as efficient action in¬ 
dependently. The berry of Razoumofskya is, therefore, to be 
classed as a sling fruit.” A similar method of dissemination has 
since been described by Mr. George J. Peirce* in Arceuthobium 
occidentals, and it has been observed, also, in the New England 
mistletoe, Arceuthobium pusillum. 
Collectors of mistletoe have noticed that the seeds will germi¬ 
nate on almost anything—bark, branches, leaves, pine needles, a 
cactus thorn, a board fence, or a barbed wire, anywhere, so long 
as the air is moist. Of course, germination will not be ultimately 
successful unless the seed fall upon a tree trunk or branch. 
When the seeds fall they become firmly attached to the host by 
means of their mucilaginous coating. The hypocotyl then makes 
its appearance and always turns toward the host. When it has 
reached the bark it becomes pressed and cemented to the surface, 
and flattens into a disc-shaped organ (Figs. 54, 56, 57). 
Reiche thus describes a very unique process which takes place 
in the course of germination of the Chilian mistletoe, Phrygilan- 
thus aphyllus, parasitic chiefly on a species of cactus: “ The 
radicular end of the embryo which has been affixed perhaps at 
some distance from the surface of the epidermis of the host plant, 
probably on a thorn, elongates to an extraordinary length, which 
varies more or less according to circumstances. If the seed has 
* Peirce, Geo. J. The Dissemination and Germination of Arceuthobium 
occidentale, Ann. Bot. 19: 99-113. January, 1905. 
