40 BULLETIN 817, U. S. DEPT. OF AGRICULTURE. 
days after the last is greater than that of the worms from the pig- killed 62 
days after the first feeding and 15 days after the last. . 
Experiment No. 19. 
Our failure in Experiment No. 18 to infect all the animals that were fed eggs, 
and to get massive infestations, together with the fact that our check animals 
became infested, led us to repeat the experiment. About this time the finding 
of ascarids in the lung of a young pig, as already recorded (Ransom and Fos- 
ter, 1917), and the fact that young animals have long been known to be par- 
ticularly susceptible to parasitic infestation, suggested that more successful 
results from infection experiments might be obtained if very young pigs were 
used as subjects. 
With the idea of obtaining animals as young as possible and to reduce the 
chances of prior infection it was decided to take a pregnant sow, eliminate 
all ascarids by treatment, place the sow in a clean pen for farrowing, and 
feed the little pigs with Ascaris eggs as soon as they could be handled. 
After numerous disappointments, a pregnant sow was procured, which, how- — 
ever, gave birth to 5 pigs before it could be examined and treated for Ascaris. 
Two weeks after the birth of the pigs (of which 2 only remained alive), the 
feces of the sow were examined. One Ascaris egg was seen in the first exam- 
ination and others in a subsequent examination. There was considerable 
doubt after the first examination whether the single egg seen came from a 
contamination of the fecal sample or indicated a slight infestation. At any 
rate it was evident that if the sow was infested the little pigs had already 
had an opportunity to pick up eggs from the sow’s feces, and it was therefore 
decided not to disturb the sow by anthelmintic treatment, but to proceed 
directly with the experiment on the pigs. 
September 22, 1917: Dosed one of the little pigs with culture of eggs of 
Ascaris suum. Pig 15 days old when treated. 
September 29, 1917: Pig died 7 days after dosing with Ascaris eggs. 
October 1, 1917: Post-mortem of pig. Ascaris larve numerous in lungs, 
trachea, and pharynx. None found in liver, spleen, esophagus, small or large 
intestine. Larve from the trachea varied from 0:67 to 1.33 mm. in length, 
0.03 to 0.06 mm. in width, with esophagus 0.12 to 0.21 mm. in length. 
October 4, 1917: Fed second pig with 5 c. « of a culture of eggs of Ascaris 
suum. Pig now 27 days old. 
October 16, 1917: No signs of pneumonia. 
November 10, 1917: Second feeding of Ascaris eggs. 
November 17, 1917: Killed pig 44 days after the first feeding, 7 days after 
the second. Liver and lungs both show numerous petechie similar to those 
found in other experiment animals and associated with the invasion of these 
organs by Ascaris larve. However, no larve were seen in the preparations 
examined. The small intestine contained S immature Ascaris, 3 of which 
were accidentally cut by the enterotome. The remaining 5 measureGé as 
follows: Length, 88 mm., 78 mm., 70 mm., 65 mm., and 60 mm.; width, 1.5 
mm., 1.3 mm., 1.2 mm., 1 mm., and 1 mm. 
November 28, 1917: Feces of sow examined; several Ascaris eggs seen. 
November 30, 1917: Sow killed: 7 Ascaris in small intestine, measuring 16 
to 21 em. long. 
This experiment, like the preceding. is open to the criticism that outside 
sources of infection were not excluded, since the pigs for the first month of life 
were in intimate association with the mother which at the post-mortem was 
proved to have been infested. This, however, has no bearing on the findings 
