WORM NODULES IN AUSTRALIAN CATTLE. 333 



(fig. 33c and 34), apparently due to excretory tissue, as to make 

 it difficult to find any hypodermis or sub-cuticular tissue at all, and 

 even on occasion to determine the boundary between this and the 

 protoplasmic meshes of the muscle cells. One of the cavities in 

 this structure near its centre is often more definite than the re- 

 mainder, and evidently represents a normal excretory passage. 

 Apparently the lateral bands are chiefly composed of what is 

 potentially excretory tissue which may become more or less vesi- 

 cular, or may be traversed by one or more definite canals that pass 

 along one side of the body. On the other side it may be reduced 

 almost and sometimes quite beyond recognition, at all events at 

 parts. This asymmetry is totally unlike anything which we have 

 been able to find in the Uterature at our disposal, though possibly 

 it is not unique In that anterior part of the body in which the 

 four longitudinal bands are well defined, the excretory canals are 

 most clearly seen in those parts where the lateral band shows the 

 more marked division into two halves ; the canals are then situated 

 some distance below the cuticle and between the two halves of the 

 lateral bands, and are sht-like in character {see fig. 37). 



Near the level of the excretory pore two broad projecting 

 ridges from the lateral lines {see fig. 35) approach the centre of the 

 body cavity, near which they become much thinner and more 

 sharply defined. They then unite, forming a narrow band almost 

 homogeneous in nature as are the ridges ; this runs ventralwards 

 to the mid-ventral hne. In each ridge can be traced a propor- 

 tionally very small but distinct lumen, the lateral excretory vessel. 

 Each of these is continued down into the median portion, and may 

 further be traced to the very minute excretory pore which opens 

 as described above. 



Reproductive System — Male. — So far as w^e have been able to 

 determine, the male reproductive organs are single throughout their 

 length. The single wide vas deferens crowded with developing 

 sperm occupies a large portion of the body cavity, compressing the 

 intestine. It passes back to open as usual into the cloaca by the 

 ductus ejaculatorius. 



The two unequal spicules {see fig. 10) in our specimens are 

 respectively 0.148 to 0.155 mm. long, by 0.0078 to 0.01 mm. wide, 

 in the middle of its length, and 0.078 to 0.094 mm. long by 0.0061 

 to 0.0078 mm. wide. There is thus evidently a variation in the 

 lengths of the spicules, but we do not find such a variation as is 

 indicated by Cleland and Johnston, who have given as the respective 

 lengths of these spicules 0.14 and 0.047 mm., and 0.197 and 0.082 

 mm. in their two reports. Both are hollow and have the usual 

 funnel-shaped opening at the inner end and closed distal end. The 

 longer spicule, which is the left-hand one, is usually once twisted 

 and has a finely pointed distal end. The right-hand shorter spicule 

 has an enlarged shoe, or boat-shaped outer end, not unlike that 

 seen in such Filariidae as some species of Oxyspirura, the grooved 

 upper surface serving for a guide for the sharp end of the long 

 spicule. 



