385 
ON THE LIFE HISTORY OF ASCARIS LUMBRICOIDES, L. 
PART IV 1 . 
By F. H. STEWART, D.Sc., Major I.M.S. 
(With Plate XX.) 
Ransom and Foster have published a preliminary account of experiments 
on the life history of Ascaris lumbricoides in the Journal of Agricultural Research 
of 19th November, 1917. They found that a repetition of my experiments 
on the feeding of rats and mice with ripe Ascaris eggs gave results agreeing 
very closely with those recorded by me in the British Medical Journal of 
July 1st, October 7th and December 2nd, 1916, and in Parasitology of February 
1917. 
In addition to these experiments, they made further attempts to infect 
pigs with Ascaris suilla, but with negative results. 
Their experiments were conducted on pigs several months old, and they 
suggest that the failure of these, and of other experiments, may have been 
due to the animals employed being past the age of greatest susceptibility 
to infection. 
In an experiment conducted by them in September, 1917, ripe eggs were 
administered to a pig two weeks old. This animal died seven days thereafter, 
and Ascaris larvae measuring from 0-7 to 1*2 mm. were found in the lungs, 
trachea and pharynx. This experiment agrees with those published by me 
in the Indian Medical Gazette of August, 1917, and in Parasitology of January, 
1918. Ransom and Foster also found an Ascaris larva in a fragment of lung 
of a pig, which had died from unknown causes, in the intestine of which 
they also found numerous immature Ascarids, the largest about 50 mm. in 
length. 
They state that guinea pigs are susceptible to infection with Ascaris larvae. 
I have recently been able to perform three further experiments on young 
pigs 2 , of which the following account may be given: 
1 and 2. To each of two sucking pigs, aged four days, about 22,000 ripe 
eggs of Ascaris suilla were given. The eggs were 31 days old, and contained 
1 Part I, Parasitology, ix. p. 213; Part II, x. p. 189; Part IIJ, x. p. 197. 
2 I wish to express my thanks to the following gentlemen who gave me the assistance required 
to carry out the above experiments: Dr Keatinge, Principal of the School of Medicine, Cairo, 
Mr Branch, Chief Veterinary Inspector to the Egyptian Ministry of the Interior, and Mr Casdagli. 
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