WORM NODULES IN AUSTRALIAN CATTLE. 323 



by Cleland and Johnston. It is true that occasionally on incising 

 the muscle immediately over a small tumour it may extrude, but 

 this is generally because when the carcase is hung up and "dressed" 

 the pectoral muscles are in a condition of great and unnatural 

 tension, but while the nodule with some of the loose surrounding 

 tissue may be then readily removed, it is not always the case, and 

 in any circumstance cannot be termed " readily enucleated." 



Occasionally evidence of recent haemorrhage in the periphery 

 of the nodule may be detected. Probably this is always the result 

 of the falling of the animal when stunned prior to bleeding, for we 

 have never observed it in tumours from the hind quarters. 



The blood vessels supplying the nodule are always very distinct, 

 generally tortuous to an extraordinary degree, no doubt owing to 

 the frequent partial displacement of the nodules. The walls of 

 these vessels, particularly the arteries, are especially thick and 

 the lumina comparatively narrow. 



The size of the nodule, as does the space occupied by the 

 parasite within, varies very considerably. Generally speaking, the 

 size of the former is that of a marble, about 2 cm., but it is not 

 uncommon to find it reach that of a walnut, 3.5 cm. Occasionally 

 we have found an individual nodule the size of a mandarine orange, 

 about 5 cm., one of the largest measuring 11 cm. by 8 cm. In our 

 experience, although it is very rare to find a nodule of less size 

 than that of a small marble, they may be found as small as a split 

 pea, 6 mm. in diameter, but then only after careful search through 

 a large number of animals. On section the tumour is seen to be 

 composed of a very dense fibrous wall {see figs. 1, la, and 2), which 

 varies very much in thickness in different nodules, enclosing a 

 tightly-coiled mass of worm "xx" in tunnels, and lying bathed 

 in a small quantity of opalescent fluid {see also figs. 30 and 32). 

 This fibrous capsule has no general relation in thickness to the 

 space occupied by the parasite ; for example, in one nodule 

 measuring 7 cm. in diameter the worm-area was 15 mm. in diameter, 

 and in another measuring 11cm. by 8 cm. the worm-area was 

 only 9 mm. {compare fig. 2). Notwithstanding this, as Cleland and 

 Johnston stated, the worm-area shows little variation in com- 

 parison with the thickness of the capsule. Further, although the 

 worm-area is usually centrally situated, it is not invariably so, 

 especially in the flattened ovoid tumours. 



Calcareous degeneration is not uncommon, and occasionally a 

 purulent form of degeneration may be seen in which fragments of 

 the dead parasite lie free. Often these degenerations attack only 

 one portion of the worm-area, the other containing still unde- 

 generated parasite with living larvae. These degenerations appear 

 solely to affect the parasite and the tissue between the coils. De- 

 generated nodules may be found in any animal, but the older the 

 host the greater the likelihood of their presence, as already shown^ 



Movement of Parasite. — Careful examination of the cut surface 

 of a nodule taken from an animal soon after slaughter enables one 



