MONOGRArn OF THE LABOULUENIACE-E. 205 
lY, figs. ] and 3) the basal cell sends into the body cavity of the host a copiously 
branched and well-developed rhizoid-like 
continuous with that of the basal cell. 
of which is apparently 
In cases where a typical foot is formed, it may constitute a cell distinct from tlic 
basal cell of the individual, as is at least often tlie case in Sligmatomf/ccs Bonn (Plate 
I, fig. 14), a condition which may very likely exist in many other instances, althou^di 
obscured by the blackening already mentioned. Tn some instanrcs this blackening 
involves more than the basal cell of the mnture plant, as in some species of Cerato- 
myces (Plate XXV, figs. 15 to 17). 
In forms like those just mentioned in which a definite hanstorium Is present, it is 
quite evident that this organ constitutes the means by which the parasite absorbs 
from its host the nourishment necessary for its growth, and at the same time serves 
to fasten it securely. In the great majority of instnnces, however, II Is probable that 
there is no intrusion of any kind from the ordinary form of blackened foot into the 
substance of the host. That this is the case may be clearly .seen in prcparafldus in 
which the parasite is shown attached to some transparent portion of the host's integu- 
ment, as in fig. 4, Plate III. In the specimen here represented several individuals 
were fixed to the surface of the thin integument of one of the abdominnl segments of 
the host, the substance of which was perfectly transparent, .so that by inverting the 
piece to which they were attached, so as to view its lower surface, one could observe 
with accuracy the- relation of the adherent portion of the foot to the chitinous surface 
to which it is applied. In such a specimen it is evident that this sucker-like adherent 
portion consists of a flat area in the closest contact with the chitin of the integument, 
d consisting of a thin memb 
gh which the absorption of 
place, bordered, as in the figure cited above, by the thick base of the indurated 
of the foot proper. It should be 
Peyritsch fig 
of a fly's integument which indicate a slight penetration through the po 
als in the case of Stigmatomj 
In addition to its function of 
the foot may, in some of 
the aquatic genera more particularly, perform the office of a fulcrum on which the 
plant is supported and by means of which it is allowed a certain freedom of motion 
which it could not otherwise attain. This is effected through the more or less sudden 
and distinct enlargement of the foot above its point of attachment. The rounded ful- 
crum thus produced rests on the surflice of the host, allowing the body of the plant, 
although appressed, to lie free from the insect and to roll upon it from one side to ihe 
other, as far as the elasticity of the attached portion will permit. This is most clearly 
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