WORM NODULES IN AUSTRALIAN CATTLE. 331 



In the anterior end of the body of several worms, but especially 

 clearly in specimen C, were to be seen tliree small brownish yellow 

 disc-like structures, the largest of which was 0.0189 mm., the 

 others 0.0146 mm. in diameter, lying in the body cavity. They 

 consist of about a dozen highly retractile yellowish granules, which 

 are larger in the larger structures. Their position, in relation to 

 the other organs of the body cavity, is indicated in fig. 6. 



Muscular System and Longitudinal Bands. — The division into 

 four quadrants usually seen in a transverse section of a nematode 

 is in Onchocerca gibsoni very obscure, and often not really present 

 through the greater part of its length {see figs. 32-34). A diagram- 

 matic representation of what appears to be normal for the main 

 length of the male and female worms is given in fig. 36. This shows 

 practically only a dorsal and ventral part of the musculature, 

 separated by more or less distinct lateral bands. Although shown 

 almost symmetrical, these bands are nearly always strongly 

 asymmetrical in the female {compare figs. 32-34), that on one side 

 or the other being hardly noticeable. We have not been able to 

 find any definite relationship of these reduced lateral bands to the 

 interior or exterior part of the nodule, such as we thought possible. 



When any particular coil is close to the boundary of the 

 worm area, then more often the better developed band is towards 

 the periphery of the nodule, but the reverse is often found towards 

 the centre of the worm mass. The dorsal and ventral median 

 bands are not distinguishable, their position being only detected 

 in rare cases by very small dorsal and median nerve strands {com- 

 pare fig. 36). The whole body wall is very thin, giving a relatively 

 large body cavity, which only occasionally and in parts contains 

 a granular material which nearly fills it, presumably coagulated 

 haemolymph. 



In transverse section the irregular ridges of the cuticle are 

 seen as papillae-like points here and there on the surface. The 

 hypodermis is usually thin, and embedded on its inner surface are 

 the contractile parts of the muscular elements, which have the 

 general appearance of a radiate border to the hypodermis. The 

 inner protoplasmic parts of the muscles are vesicular, forming 

 irregular meshes on the inner side of the body wall. These 

 characters of the musculature are often hardly distinguishable, so 

 attenuated do they become in the thinning out of the whole wall. 



In the anterior part of the bodies of both male and female 

 worms, however, the structure of the body wall more nearly 

 approaches the nematode structure {compare fig. 37). This is only 

 to be found, however, in that anterior part of the worms which 

 does not exceed about 0.095 mm. in the male and 0.175 mm. in 

 the female. Here, as will be seen from the figure, especially in the 

 female, the lateral bands are strongly developed, and together 

 occupy about two-thirds of the entire body circumference. Some- 

 times each shows traces of a division into dorsal and ventral halves. 



