1 Junz, 1898.] QUEENSLAND AGRICULTURAL JOURNAL. 491 
lung hydatid caused by the inhalation of the dried and pulverised droppings of 
sheep dogs. It is the ‘‘materies morbi’’ made on the spot. The eggs or 
minute ova of the adult tapeworm measure only 5+, of an inch in length, and 
contain embryos which ultimately develop into hydatids. They are most 
commonly conveyed into the stomach of the future victim by the drinking of 
water, but in all probability often by allowing dogs having these tapeworms to 
lick the face or hand. The writer has on more than one occasion seen dogs 
lick the faces of their owners. Children are especially apt to allow dogs they 
like to show their affection in this dangerous manner, and he knows of a case 
in Sydney where two children of one family died from hydatids, and it was 
found that they were the constant companicns of some pet dogs. The following 
instance is taken from the late Dr. J. D. Thomas’s work on hydatids :— 
“In February, 1879, a child aged two years and one month was brought 
to the writer, suffering from. an enlargement of the liver, which had been first 
noticed by his mother about six weeks previously. The tumour was aspirated 
and found to be an hydatid cyst, containing three fluid ounces of clear watery 
fluid. The extreme youth of the child induced the writer to investigate closely 
the probable source of infection, and it was concluded, with almost absolute 
certainty, that it could be traced to a bulldog, which was a constant companion 
of the child. The mother had noticed frequently that the child was in the 
habit of sucking the bones which had been gnawed by the dog and lay on the 
ground about its kennel, and thus, without doubt, the infection had been 
conveyed from the dog to the child.” 
Such cases are unlikely to be common, as most pet dogs are fed well. 
under the supervision of their owners, and do not have to hunt round butchers’ 
shops and dustbins for a living as the vagabond dogs do. We must conclude, 
therefore, that for all practicai purposes the domestic dog is the direct source 
of hydatid infection in man and in the domestic herbivora. But the dog must 
receive its infection by eating the viscera, or bowels, of animals containing 
hydatid cysts; and it may be regarded as certain that before the human body 
can be infected the eggs of the Zenia must be received into the system, for 
there is no evidence that the hydatid cyst of one host can directly produce an 
hydatid in another when swallowed by the latter. The popular opinion that 
hydatids in man are caused by eating underdone mutton is totally unfounded. 
A doctor informed the writer, when both were engaged in experiments in 
connection with this disease in sheep, that in the event of man swallowing a 
cyst from a sheep it would have no ill effect. 
The spread of Echinococcus will be determined by four factors :— _ 
1. By the number of dogs in the country. 
2, By the opportunities existing for enabling the eggs bred in the dog to 
be swallowed by domestic Herbivora and man. : 3 
83. By the number of domestic Herbivora, sheep, oxen, pigs, &c. 
_ 4. By the frequency with which dogs eat the organs of intected sheep, 
&e., containing living hydatids. 
Therefore, the favourable conditions, if it may be so put, for the spread of 
the: disease, are as follow :— 
A district with many sheep, where the dogs are allowed to feed on the 
offal; the water supply scanty, and procurable only from swamps and dams, on 
the banks of which dogs may deposit the eggs of the tapeworm in their 
excrement, to be blown in by the winds, or washed in by the rains. It sheep, 
oxen, and pigs are few, hydatids will be scarce. If dogs are few, then the 
tapeworm will also be scarce; and allowing the existence of the dogs, they will 
not have the tapeworm if they do not eat organs containing the cysts. Should 
the supply of water be a running one, there is very little danger of sheep 
swallowing the particular drop of water containing the dangerous egg. 
The natural conclusion is, then, that the country with the greatest number 
of dogs is the most liable to the hydatid infection. It has been computed that in 
England there is one dog to every fifty: inhabitants, and in Iceland one dog to 
‘ 
