21 Guinea pigs were experimentally infested by rggs of Neo ascaris vitulorum, 3 Guinea pigs were sacrificed at different times : 3, 18 hours, 1, 2, 3, 5 and 7 days postinfestation. Hatching occur red in the ileum after 3 hours. 18 hours later, the larvae were found in th- peritcreal cavity and liter. Within 2 days the migratory tra cts were found in the liver, 1.123s, brain, and kindeys. Migration through liver to the lungs was a constant route in all guinea pigs. Somatic migration through thc brain and kidneys was of sporadic incidence.
Tissue alterations were mechanical damage from larval migra tion and variable degrees of dystrophic changes in the parenchy matous organs. Reaction to the presence of parasites was not ex pressed except in the lungs. Leucocytic response was observed in which eosinophilia was predominating.