THE MISTLETOE. 
275 
may be checked or altered. A common type of abnormal growth 
is a bunch of small, upright branches forming a “ witch’s broom.” 
This abnormal growth was not observed on any of the mistletoe¬ 
bearing trees or bushes in Jamaica, nor did the host plants seem 
to suffer in the least; yet the pines in this country gradually die 
from the effects of the parasite. 
The embryo of the mistletoe, as it lies within the pericarp, is a 
bright green because of the abundance of chlorophyll which it 
contains. It does not undergo any period of rest, but is ready to 
continue its growth as soon as it falls on a suitable substratum. 
The question is still to be settled whether the “ seed ” of the 
mistletoe is a true seed, a naked ovule without integuments, or 
Fig. 57. Seedlings of Vis cum album, (a) Containing a single germi¬ 
nating embryo. ( b ) Two germinating embryos. The cotyledons of one 
of them can be made out. From preparations by Professor F. E. Lloyd. 
rather a naked embryo enclosed in a fleshy pericarp. As for the 
embryology of the parasite, nothing more is definitely known 
concerning it than in the time of de Candolle, largely because of 
the rapid disintegration of the delicate cells of the young flower in 
the process of “ fixing,” a trait peculiar to parasitic plants. 
When the history of the embryo-sac is worked out, it may throw 
some interesting light on the physiology as well as on the mor¬ 
phology of parasites. It is a problem on which the writer is at 
present working. 
