42 BULLETIN 817, U. S. DEPT. OF AGRICULTURE. 
It might appear from these experiments that Ascaris luwmbricoides can not 
develop beyond the lung stage in pigs, and that therefore there is a biolegical 
if not a morphological difference between the Ascaris of man and that of pigs, 
the Ascaris of man not being able to develop in the pig. Of 4 pigs fed very 
large doses of eggs only 2 showed any infestation, and in neither of these did 
the worms develop beyond the lung stage. It is true that 1 of the 4 pigs died 
when the parasites were actively migrating out of the lungs, and in this case 
the death of the host certainly interfered with further development of the 
larvee, but of the 3 remaining pigs, all of which received large numbers of eggs, 
only one showed any infestation, and apparently in this case the larve that 
succeeded in reaching the lungs never developed further. 
It is, however, hard to believe that the digestive apparatus of the pig is so 
different from that of man that an Ascaris morphologically indistinguishable 
from the form found in man would be unable to develop at least to an imma- 
ture stage in the intestine of swine. As shown in another experiment Ascaris 
suum may develop in lambs to immature worms of considerable size, and it may 
also be noted that Jammes and Martin (1906) succeeded in rearing Ascaris 
vitulorum to a considerable size in a man to whom the eggs of the parasite 
lad been administered. Yet the difference between the digestive apparatus of 
sheep and swine is certainly greater than that between swine and man, and 
undoubtedly the Ascaris vitulorum of calves is a distinct species from Ascaris 
lumbricoides of man. The failure to obtain at least immature worms if not 
mature worms in the intestines of pigs following the feeding of eggs of A. 
lumbricoides can therefore scarcely be explained upon the basis of a biological 
difference between the Ascaris of man and that of the pig. 
Experiment No. 22. 
March 2, 1918: Fed a 2-day-old lamb with about 3 cubic centimeters of a 
culture of Ascaris suum eggs which had been prepared January 9. 
June 13, 1918: Lamb killed 103 days after feeding. Apices of lungs consoli- 
dated. No Ascaris larve found in the lungs. Duodenum showed numerous 
ecchymotie spots and 50 half-grown Ascaris, 12 males, 38 females. Males were 
60-110 mm. long, average 88 mm.; females 60-132 mm. long, average 91 mm. 
Three worms were over 130 mm. long. Most of the specimens were between 75 
and 110 mm. 
Experiment No. 23. 
July 3, 1918: Fed a 4-day-old kid with a large dose of eggs of Ascaris suum 
incubated since April 4, 1918. The kid showed no ill effects from this dose. 
July 20, 1918: Second feeding with Ascaris swum eggs, one-half ounce of the 
culture being given in milk. 
July 27, 1918: The kid shows symptoms of pneumonia 24 days after the first 
feeding, 7 days after the second feeding. High temperature, abdominal breath- 
ing, occasional hard, dry cough; animal appears listless, but appetite is still 
good. Eyes are somewhat inflamed, coat staring, animal lies down most of 
the time. 
July 28, 1918: Same symptoms as before. Gave three 1/50-grain strychnin 
tablets as a heart stimulant. 
July 30, 1918: Kid refuses all food, grows rapidly worse, and dies at 4.30 
p. m., 27 days after the first feeding, 10 days after the second. 
July 81, 1918: Post-mortem. Liver shows extensive cirrhosis, but no laryze 
are seen. Lungs intensely hemorrhagic and edematous; loaded with larvz 
ranging from 0.95 to 1.85 mm. in length, most of the forms measured being well 
