42 BULLETIISI" 817, U. S. DEPT. OF AGRICULTURE. 



It might appear from these experiments that Ascaris lunihricoides can not 

 develop beyond the lung stage in pigs, and that therefore there is a biological 

 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 

 larvte, but of the 3 remaining pigs, nil of which received large numbers of eggs, 

 only one shoAved any infestation, and apparently in this ease the larvje that 

 succeeded in reaching the lungs never developed further. 



It is, however, hard to believe that the digestive apparatus of the pig is so 

 diiferent 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 

 sminv 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 

 vitnlorwn to a considerable size in a man to whom the eggs of the parasite 

 liad 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 vitulormn of calves is a distinct species from Ascaris 

 lunihricoides 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 smim eggs which Imd been prepared January 9. 



June 13, 1918 : Lamb killed 103 days after feeding. Apices of lungs consoli- 

 dated. No Ascaris larvae found in the lungs. Duodenum showed numerous 

 ecchyniotic 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 siiuni 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 31, 1918: Post-mortem. Liver shows extensive cirrhosis, but no larv.ie 

 are seen. Lungs intensely hemorrhagic and edematous; loaded with larvpe 

 ranging from 0.95 to 1.85 mm. in length, most of the forms measured being well 



