1887, ] BOTANICAL GAZETTE. | 175 
The proper parasites do not exclusively belong to the 
class of fungi. You are familiar with the Indian pipe (Mon- 
otropa) and dodder (Cuscuta), which are our common repre- 
sentatives of parasites, which are found ina comparatively 
small number of orders of Phenogams. As chlorophyll is 
Wanting in these plants, we are forced to assume that the para- 
Sitism is as complete asin fungi. You, also, will recall the mis- 
tletoes and the Gerardias, together with other members of the 
Scrophulariacea?, which are not proper parasites in the sense 
in which we have already spoken, but may rather be called 
partial parasites ; because, while they have chlorophyll and 
ganic material, they still depend in part on material taken 
from other plants to which they are more or less closely at- 
tache!. In the discussion of the evolution of parasites, the 
phenogamic parasites, however, are o comparatively little 
“portance ; because, by means of their flowers and fruit, 
to, well recognized orders of Phenogams, and the question 
of the origin of the parasites themselves is not to be sepa- 
Tated from the question of the origin of Phanogams as a 
whole, so that, in this case, we have only to account for the 
modification of the organs of vegetation whose greater sim- 
Plicity may be explained by the loss of leaves and other 
assimilating organs which have become unnecessary to plants 
lated by other plants. In short, as far as parasitic Pheno- 
ams are concerned, they may be regarded as degenerate 
forms of other Phenogams, for, in a plant, the inability to 
assimilate inorganic material should be regarded as a de- 
Staded condition in which the chances of survival are dimin- 
‘shed unless some extraordinary provision is made for repro- 
duction, which is not the case in Phenogams, whatever may 
© true of fungi. 
. Whether any proper parasites are to be found among alg@x 
's @ question on which there is a difference of opinion. ‘or 
my Own part, I am unable to recognize any proper parasite 
-nong alge, although it is tolerably certain that a number of 
forms generally classed among algz may be regarded as par- 
tal parasites, This point, however, can be better consid- 
ered later on | : 
Let us next briefly consider the mutual relations which 
€xist_ between parasites and their hosts—that is, the sub- 
Stances, dead or living, on which they are growing. At first 
