The adult organisation of Paragordius varius. 401 
the hypodermis. Obviously these disarrangements of the muscular 
layer in this posterior region of the body are due to the ingrowing of 
the cloaca and of the caudal nerves from the hypodermis. 
There is thus no vertical muscular diaphragm in the male con- 
necting the posterior end of the cloaca with the dorsal body wall, as 
has been described for the genus Gordius. 
Literature on the musculature. VrJDovskY (1886) first 
discovered the nuclei of the muscle cells. He described the muscle 
cells of Gordius, especially of the male, as branched; but an examination 
of his figures on this point shows that he probably confuses the net- 
work of intermuscular substance with the muscle cells themselves; 
this explains why in one species he describes the nucleus as lying on 
the outer side of the cell, and why he denies the occurrence of an 
intermuscular substance; this appears very plain from his fig. 48. In 
his later paper (1894) be brings observations to slow that what I 
have called “intermuscular substance”, probably arises from the 
muscle cells. Vıtrzor (1887) notices the intermuscular substance, 
which he states to be the result of the fusion of the walls of the 
embryonic cells which give rise to the muscle elements; he denies 
the occurrence of muscle nuclei in the adult stage; and notes finding 
in the embryonic stages forms of muscle cells similar to those of 
Nematodes. CAMERANO (1888a) concludes the muscle elements are of 
the nematodan type. RoHDE (1892) quite closely confirms VEIDOVSKY’S 
account; he distinguishes a “Rindenschicht” which contains the “Muskel- 
säulchen”, and an axial “Marksubstanz” containing the nucleus; he 
finds the muscle cell often open on its inner surface, and so con- 
cludes that it is of the nematodan type. None of these writers could 
find the mode of innervation of the musculature; and all but VEJ- 
DOVSKY maintain that the muscles are of the type found in Nematoda. 
V. The Intestine. 
In regard to the alimentary tract Paragordius shows few differences 
from Gordius, and since the latter has been well described in regard 
to this structure, only a brief account need be given here. 
In the adult stage the whole intestine appears very degenerate 
in comparison with the preceding parasitic stage, the nuclei and cyto- 
plasm katalytically modified, and the cells much smaller; further, in 
no adult individual was any trace of food substance to be seen in it, 
so that these worms probably take no nourishment in the adult, 
aquatic stage. 
