WORM NODULES IN AUSTRALIAN CATTLE. 321 



were slaughtered and examined. The former contained twenty-five 

 and the latter thirty nodules. All these cows were paddocked, that 

 is, pastured in comparatively small areas (say, 50 to 200 acres), and 

 were used for dairy purposes. No doubt, examination post-mortem 

 of the two young cows would have disclosed quite as many nodules 

 in the inter-muscular spaces as were found in the old cows. 



Second Station. — (Notorious for prevalence of these nodules.) 

 Yearling heifer examined post-mortem. Twenty nodules in 

 brisket, varying in size from a pea to a large marble. 



Another yearling, probably 10 months old, killed and examined, 

 showed twenty-four nodules, a group of five being clustered at one 

 place over the sixth and seventh intercostal spaces. These varied 

 in size from a split pea to a walnut. 



Calf, about 3 months old, running with mother, killed and 

 examined ; no nodules could be detected anywhere. 



Third Station. — In same district as previous stations (recog- 

 nised as comparatively " clean "). Cow, aged 8-10 years ; killed 

 and examined. Only four nodules, each the size of a marble, present. 



Calf, 6 to 8 months old, running with mother ; killed and 

 examined. Four small nodules present. 



Heifer, 18-20 months old ; killed and examined. No nodules 

 found after very careful examination. 



(It may here be noted that on this station the cattle are 

 dipped in arsenical solution every three to four weeks in order 

 to combat cattle-tick infection, whereas on the other stations 

 •dipping is not carried out so frequently or so thoroughly). 



It may be observed that the older the animal, generally 

 speaking, the greater the tendency for the parasites to be degene- 

 rated. For example, the parasites of all the nodules in the 17- 

 years-old cow, and the majority of those in the 14-years-old cow, 

 were degenerated and calcified ; while in the 8-10-years-old cow 

 three of the four nodules contained degenerated worms, one of 

 which was partially calcified, lying free in a muco-purulent fluid. 

 In the younger cattle no degenerated worms were found. 



These observations indicate very clearly that the most general 

 period in the life of the host when the filaria enters or at least 

 establishes itself in the system is during youth, probably the first 

 year. They have, therefore, an important bearing on the general 

 life-history, as will be discussed later. 



New Growths (Nodules) induced by Parasite. 



Location and Number. — In spite of the observations of some 

 to the contrary, the experience of one of us (J.A.G.), gained from 

 the examination of over 700 cattle affected, is that the nodules 

 are invariably confined to two distinct and separate situations. 



The commonest situation is the region of the brisket, chiefly 

 the triangular outline formed by the junction of the ribs with the 

 costal cartilages, especially between the fourth and sixth ribs, but 



