178 
PRESIDENTIAL ADDRESS. 
To refer only to plant life, the lowly toadstool grows as a 
parasite on decaying vegetable matter, while the herbaceous 
beauties of cow-wheat, eyebright, and such like obtain their food 
from the neighbouring grasses. They, however, attach them- 
selves to these roots after the seeds have germinated in the 
ground, and as growth proceeds the rootlets of the young plants 
fasten on to the grasses, and utilise their roots to supply nourish- 
ment. A similar springing into active life before getting their 
food from others belongs in fact to all the British parasites. The 
exception is the Mistletoe, and looked at in this way the 
Mistletoe is the most degenerate of all our parasitic plants, be- 
cause its seeds germinate on the living tissue of its host, and make 
no attempt to start life in the ground like the others. It has 
selected trees as its host, and in time will impoverish the most 
vigorous branch, in the same way that other plant parasites 
injure the hosts on which they have made their home. 
The Mistletoe lives on year by year and grows slowly, 
apparently needing the sap of trees to supply its nourishment. 
The reason of this need cannot be decided so far, and Darwin 
held strong views about the selective power of plants, and char- 
acterised it as preposterous to claim any one cause for their 
parasitic habit. He, and others since his time, have assigned 
many reasons why a variety of causes must be weighed before 
being tied down to one. This much, however, can be said of 
the Mistletoe's selection of particular kinds of trees, that a com- 
parison of the outer coats of their branches shows that all of 
them are covered with a soft, sappy tissue. Through these soft 
coatings the pegs or roots given off by the Mistletoe seeds can 
readily penetrate, and at once enter upon a food supply of sap. 
The way then that the Mistletoe begins its life is by the naked 
seed germinating directly on the tree, and how it gets to a suit- 
able place on the bark, and how it continues its growth, present 
many interesting features. 
The berries when ripe are round, and contain a solitary seed 
completely enveloped in a thin glutinous pulp, which is eagerly 
eaten by birds, notably the missel thrush (hence its name) and 
the blackbird. These belong to the order of fruit-eating birds, 
which do not grind up their food in their crops, so that the seeds 
after passing through the bird still retain the power to germinate. 
This method, by which the Mistletoe is dispersed, would seem 
to have been noticed in ancient times, because the derivation of 
its name is stated by Skeats to be taken from the Scandinavian 
word "mist," meaning dirt, in reference to the manner of dis- 
tribution by birds. Other authors, it is true, go back to an 
equally early period and connect the name with the Anglo-Saxon 
"missel," different, and thus think it would mean a different 
twig to the branch on which it grows. 
The idea that the Mistletoe seed clings to the beak of the bird, 
when feeding on the berries, and is rubbed off by it on to the 
