408 @RANSACTIONS OF SECTION D. 
The most common human parasites are the hook worms (Ankylostoma and 
Nicator). Other human parasites are not more common than in temperate parts, 
while hydatids are much rarer than in other parts of Australia. The parasites 
of domesticated animals have not received much attention and only a few 
scattered records occur. The most outstanding parasite of the dog is Diro- 
filaria immitis, which infects the heart and lungs and appears to cause much 
mortality. In rats the characteristic parasite is the large Kchinorhynch, 
Gigantorhynchus moniliformis. 
The parasites of marsupials and monotremes are interesting. Filaria worms 
are fairly common in wallabies and opossums, while wallabies frequently har- 
bour a large mass of Strongylids in their stomach. The Echidna is frequently 
infected with tapeworms and a curious little red, spiral-shaped Nematode 
hitherto undescribed. Similar Nematodes occur in fruit bats and snakes. Not 
the least interesting mammalian parasite ‘is that described by S. J. Johnston 
from the dugong, a Trematode which possesses an entirely new type of structure. 
The birds do not show many parasites that are peculiarly Australian or 
tropical. This is probably due to their migratory habits. The reptiles and 
frogs afford several forms which are typically Australian and a few which 
appear to be essentially tropical. ° 
It is amongst the fishes that we find the most distinctive parasite fauna. 
This applies particularly to Trematodes, and it will probably be found that a 
large proportion of the Australian Trematode parasites of fishes represent new 
generic types, and in some cases perhaps new family types. 
On the migration of Onchourea lurvee through the capsule of the worm nodule. 
The life-history of the parasitic worm which causes nodular disease in cattle 
still remains a mystery. A considerable amount of experimental work has been 
done on the subject, but few positive results have been obtained. 
In 1911 T. H. Johnston published a summary of the work which had been 
done up to that date, and came to the conclusion that the most probable inter- 
mediary host is a mosquito, a louse, or a cattle-Hy. Since that time four 
important contributions have been added by Australian workers. The first of 
these was by Cleland, who made the discovery that some calves which had been 
reared on Milsom Island, New South Wales, and had never left the island, had 
become infected with worm nodules. This showed that all the factors con- 
cerned in the transmission of the disease are present on the island, and therefore 
narrows the scope of investigation considerably. Cleland came to the con- 
clusion that a biting fly or a mosquito is the most probable intermediate host. 
The second paper is by Gilruth and Sweet, who concluded that fresh 
infection only occurred in young animals. They showed that direct infection is 
improbable, and formed the opinion that some biting insect is the most likely 
transmitter. 
On the other hand Breuil performed some experiments which seemed to 
indicate the possibility of infection by means of water. He was able to induce 
larve to penetrate the unbroken skin and to emerge into water, where they lived 
a short time. His attempts, however, to infect various aquatic animals with 
these larvas were not successful. Quite recently Cleland has published further 
observations. He found that Onchocerca larve could be ingested by the stable- 
fly (Stomoxys) and live in it for several days, but he could detect no develop- 
ment ‘in these larve. He also discovered free adult worms in cattle, making 
their way through the tissues of the hind leg from the foot upwards. 
It was with the view of confirming Breuil’s experiments that the present 
work was undertaken. The technique employed was similar, but various modifi- 
cations were adopted to ascertain the effect of temperature, rainfall, &e. In 
none of the thirty experiments, however, was any positive result obtained. 
The procedure consisted in applying sterile water on a calico pad or in a 
glass vessel to the shaved skin over a nodule, and examining the water a few 
hours later. The negative results obtained in these experiments show that some 
factor was lacking which was present in Breuil’s investigations. 
Further experiments were performed with nodules excised from slaughtered 
cattle. These nodules were immersed in water under varying conditions for 
