lOS 
MOXOGPvAPH OF THE LABOULBEXIACE^. 
little if any appreciable injury on the host, and even when the latter is completely 
covered by them it shows no more marked signs of injury than is indicated by a 
grcfiter restlessness, owing perhaps to a slight irritation which they may be supposed 
to produce. This absence of appreciable injury, associated as it is with true parasitism, 
is due to i]iQ fact that the habit of growth of the plants in question is an external one, 
nnassociated, except in rare' instances, with any penetration of well-developed haus- 
toria into the body cavity, the parasite in almost all cases deriving its nourishment 
throngh at most a slight perforation of the host's integument. The hosts affected 
are all comparatively long-lived hibernating insects, and more or less continuous 
other instances, are obliged to become 
feeders: and 
present 
1 for th( 
so man} 
ion of a] 
often 
numerous 
d 
d 
1 
from which they are freed only by death. 
An external parasitism, like that of the plants in question, on hosts living and as a 
rule actively locomotive, whether in water, in the air, or on the ground, would natur- 
ally be associated with a comparatively simple structure adapted to the exigencies of 
life ; and a gl 
accompanying plates will show that such a simpl 
type form may be traced in a general way throughout the group 
A 
body 
: of 
diff 
ptacle, is fixed by means of a blackened base, or foot, to the inte^rumen 
, and consists in most cases of a very small number of cells differently arran^^ed 
genera. This receptacle gives rise abo 
vcrv 
able for 
vhile fro 
only connected with the 
P 
of 
ppendages of 
male sexual 
female organs are also variously produced fi 
few exceptions in which the pi 
ually developed. In the pe 
pe 
evcnt- 
1 
be 
fr 
a 
g 
individual, and which 
may arise singly 
abl 
num- 
prodiiccd the reproductive bod 
qui 
pects 
■emarkabl 
formed ir 
structuie, are 
f u n o; 
The 
members of 
cy become attached b 
thus formed ger 
p of 
on 
a 
blackened modifi 
of 
formation of any 
f 
face of 
■ 
ir basa 
host to 
I 
directly to new individuals by 
ty 
pec 
the 
divid 
ably wl.l.in ce.tain rather narrow limifa, for while the sn.allest species m 
y consid 
thof 
from base to tip, while by f 
millimeter m total length, a very few exceed a m 
r 
length. W 
b 
in 
of size and fund 
more than 
If 
portunities for eccentricity of for 
d 
op- 
been abundantly utilized 
I 
I 
I 
I 
I 
