218 
Development of Ascaris 
(4) Following Davaine’s experiment with the dog the writer 
administered very large doses of ripe eggs of both the Ascaris from 
man and of that from the pig to a puppy four months old. It did not 
appear to be in any way affected by the dose. 
(5) Rat G was fed with eggs of the human Ascaris 54 days old. 
The doses were repeated on the 24th and 25th. On the 26th it was 
extremely ill and breathing at the rate of 160 per minute. On the 27th 
it died. Ascaris larvae were found abundant in the lungs and hver. 
(6) A piebald mouse (mouse A) said to be one year old was treated 
with the same culture as rat G, on the 24th, 25th and 26th of April. 
On the 28th it was seriously ill, with respirations at the rate of 120 
per minute. It died on that day. Lungs and hver were richly infected 
with larvae. 
It is interesting to compare the last experiment with that of 
Leuckart’s with the mouse. Leuckart asserted that the eggs were 
passed in the faeces unaltered. The present writer found in addition 
to a few unaltered eggs a small number of free but dead larvae. It is 
probable that Leuckart did not give sufficiently large doses of eggs 
to cause the death of the animal and thus failed to observe the larval 
stages of the parasite. 
In the cases of rat C and mouse A, sections proved that the larvae 
were situated in the air vesicles of the lungs and in the blood capillaries 
of the liver close to the interlobular veins (Text-fig. 9). 
(7) A second mouse (mouse B) was taken for experiment on 5. v., 
when a small dose of ripe eggs of Ascaris suilla was administered to it. 
On 12. V., that is the 7th day after infection, it was observed to be ill. 
It was kept at that time in a box which was furnished with a darkened 
upper ledge resembling a mouse’s hole. The mouse was observed to 
leave this hole and sit in the open box. On 13. v., the 8th day after 
infection, it was killed. Larvae measuring roughly from 1 to 1'5 mm. 
in length were found in the roots of the lungs—^doubtless in the bronchi. 
One larva measuring 1 mm. and one of 1‘5 mm. were found in the 
trachea. No worms were found in the nasal cavities, liver, or ahmentary 
canal. 
(8) Having traced the infection to the air vesicles, bronchi and 
trachea of the rat and mouse it became necessary to ascertain whether 
the larvae in these situations were capable of further development 
in the definitive host. Portions of the lungs of rat D were administered 
on 16. iv. to the pig B which had been used in the experiments on 
direct infection described above. This animal was killed on 30. iv. 
