197 
ON THE LIFE HISTORY OF ASCARIS LUMBRI- 
COIDES L . 1 
By F. H. STEWART, M.A., D.Sc., M.B., Major, I.M.S. 
On Ascaris infection in Man and the Pig. 
I. In the following three experiments it will be shown that ripe 
eggs of Ascaris suilla can hatch in the intestine of the pig, that the larvae 
issuing from these eggs enter the body of the pig and pursue the same 
course through the body as in the rat and mouse. They have been 
found in the lung of the pig from the 6th to the 8th day and in the trachea 
on the 8th day. Dead larvae have been found in the faeces of the pig 
on the 11th day after infection (Expt. 6). 
Expt. 1. Sucking-pig No. 8, 20. n. 17. Nine days old, was given a very large 
dose of eggs of A. suilla 4 months old. The pig was killed, 26. n., and the pleura was 
found studded with small patches of ecchymosis, Ascaris larvae were present in these 
patches and throughout the lungs in large numbers, no larvae were found in the 
liver. No other organs examined. 
Expts. 2 and 3. Sucking-pigs Nos. 6 and 7. On 20. n., nine days old, given 
very large doses of eggs 43 days old. On 26. n. both pigs were suffering from severe 
dyspnoea and cyanosis. On 28. rr.-l. m. both pigs died during the night. 
Ascaris larvae were present in enormous numbers in the lungs and trachea, 200 
specimens were counted in a watchglass in which a fragment of trachea l" long had 
been dipped. 
II. It may be assumed that any development undergone by 
A. suilla in the pig will also be undergone by A. lumbncoides in man. 
1 This paper is a continuation of work published in the British Medical Journal, 
July 1st, Oct. 7th, Dec. 2nd, 1916, and in Parasitology, ix. 155. The cost of the animals 
used in the experiments was very kindly borne by the Government of Hong Kong and the 
work was conducted in the Bacteriological Institute of that colony. My thanks are due 
for this assistance, and I am also indebted to Dr Johnson, P.C.M.O., Hong Kong, Dr 
Macfarlane, Government Bacteriologist and Mr A. Gibson, Colonial Veterinary Surgeon, 
Hong Kong, for the interest they have taken in the research. 
The author regrets that he is obliged to publish incomplete work and pleads in excuse 
that he has been obliged to discontinue the research, not knowing when he will have an 
opportunity of resuming it. 
