216 ON THE OCCURRENCE OF " WORM-NODULES " IN CATTLE 



but not in the blood, though searched for in films taken 

 by night as well as by day, in case there should be any 

 periodicity. Since the nodules are practically restricted 

 to those portions of the animal which come in contact with 

 the ground, and since they are frequently subcutaceous 

 in situation, we were led to suggest that a fresh water 

 crustacean might act as a transmitting agent in a manner 

 analogous to that known to occur in the human guinea- 

 worm, Dracunculus medinensis. Dr. Cleland and myself 

 have not been able, as yet, to infect Cyclops and Daphnia 

 with the embryos, the latter living only a very short time 

 in water. We have, therefore, been driven back to our 

 first idea, that a biting insect or a tick might be the 

 actual transmitter. The lack of material in Sydney, and 

 the pressure of official business, prevented our following up 

 this matter as thoroughly as we wished. 



Leiper (1911, a, p. 12), arguing from the structure 

 of the embryo, believes the intermediate host to be a biting 

 insect, such as Stomoxys, Hippobosca or Tabanus, or perhaps 

 one of the Ixodidae. The Hippoboscidae may be excluded on 

 account of their absence or rarity on our cattle. Stomoxys 

 jalcitrans is a common fly in parts of Eastern Australia, 

 ftnd may be responsible for the transmission, but this seems 

 rather unlikely on account of the relatively slow, south- 

 ward extension of the condition. The same remark applies 

 to the Tabanidae. Gilruth and Sweet (p. 27) are not in 

 favour of the idea that biting flies spread the parasite, 

 for the same reason, nor do they think that ticks are re- 

 sponsible, as they state that the nodules were observed 

 long before the advent of the tick in Queensland. They 

 evidently refer to the " cattle tick " Margaropus (or 

 Boophilus) annulatus, var. australis, but there are many 

 other ticks which are known to infest cattle in Australia, 

 e.g., Amblyomma, Haemaphysalis, Aponomma, and Bhipicep- 

 halus, while an Ixodes, (/. holocyclus) attacks various animals 

 here. None of these, excepting 31. annulatus are, however, 

 common on cattle, and may be disregarded for the present 

 on that account. The calf louse {Haematopinus vituli, L.), 

 is regarded by these workers (p. 28) as being the most 

 likely transmitting agent, and point to certain facts which 

 seem to them to support their contention, viz., that the 

 infection in young and old cattle is about the same ; that lice 



