I IO 
Peirce . — The Dissemination and 
The life-history of this perennial parasite supports this view. The 
branches at first vegetate in the air, and later flower and fruit. After their 
crop of ‘ seeds ’ has been discharged they die and fall away. At this time 
no part of the parasite may be visible outside the body of the host. The 
persisting part of the parasite, embedded and concealed in the host, 
contains no chlorophyll. It corresponds with Rafflesia, Balanophora , &c., 
and at this stage is altogether different from Viscum and Phoradendron . 
When Arceuthobium becomes active again, as it does in the spring, forming 
buds and developing these into branches, it must do this work either at the 
cost of foods elaborated by itself and stored in the mass of parenchymatous 
cells of its own in the cortex and medullary rays of the host, or at the cost 
of foods drawn from the host, or both. As I saw no evidence of any great 
accumulation of foods in the parasitic tissues embedded in the host, I am 
inclined to believe that, though its aerial parts contain chlorophyll, 
Arceuthobium is a much more complete parasite than Viscum and Phora- 
dendron, and, in spite of having no sieve-plate connexions with the sieve- 
tubes of its host, that it absorbs and uses foods elaborated by the pine. 
The perennial part of Arceuthobium is probably completely parasitic so 
long as it has no aerial branches. During the many months when it has 
aerial branches it may not be a complete parasite, and may be merely 
a * water-parasite/ 
Arceuthobium , therefore, shows a distinct advance over Viscum and 
Phoradendron toward complete parasitism, and is an interesting link in the 
chain connecting independent plants and completely parasitic forms. 
Owing to the presence in the host of a perennial part of Arceuthobium , 
it is out of the question to exterminate the parasite by merely removing 
the aerial branches. The spread of Arceuthobium in a forest can, however, 
be prevented by removing the fruiting branches before the fruits are ripe. 
If this were done every two years through a series of years, and the infected 
trees gradually thinned out, the parasite could be exterminated. Thinning 
the forest, thus exposing the parasite to greater dryness during the summer 
and greater cold during the winter, would tend to keep it in check. In 
a natural forest of thick growth combatting the parasite is not likely to be 
successful. In a planted forest, carefully watched, there should be no 
danger of any great damage from this source. When we learn in America 
to take as intelligent and skilful care of our forests as we now do of our 
gardens the phanerogamic parasites will do little damage to the trees. 
As a result of the presence of Arceuthobium in the pine, the trunk and 
branches, especially the latter, exhibit considerable distortions. At a point 
where there is a bunch of Arceuthobium of considerable size, the diameter 
of the branch may be three or even four times greater than just below. 
The infecting strands of the parasite do not grow for any distance upward 
and downward through the cortex of the host. Instead they penetrate the 
