190 
Development of Ascaris 
The above facts were ascertained from the following experiments: 
(1) Experiments on Mice (1c), ( l ), (to), (p) and (r) recorded in the 
British Medical Journal, December 2nd, 1916. In these experiments 
Ascaris larvae were found in the large intestine in four out of the five 
mice used, on the 9th, 10th, 11th and 12th days after infection. Larvae 
were also found in the faeces in two cases, on the 10th and 12th days. 
(2) The following additional experiments are now recorded for the 
first time: 
Mice (q), (s), (u) received doses of eggs 23 to 32 days old and were killed between 
the 10th and 13th days thereafter. No larvae were found in the lungs, intestine 
or faeces. 
Mouse ('/;) received a dose from the same culture as (u) on September 4th. Not 
appearing ill, it received a second dose on October 21st and a third dose of another 
culture on November 13th. On the 16th day after the third infection one Ascaris 
larva was found in the faeces. The mouse was killed on the 18th day, but no larvae 
were found in the trachea or large intestine. 
Mice (w) and (*) were killed as controls without infection. No nematodes were 
found in the lungs or trachea. Oxyurids were found in the colon. No forms 
resembling Ascaris larvae in any part of the intestine. 
Mice (y) and ( 2 ) received doses of eggs of A. suilla aged 140 days and 41 days on 
Ootober 13th. On the 10th day no larvae were found in the faeces. On the 11th 
day 5 larvae in the faeces, of which 2 moved languidly in salt solution. On the 
12th, 13th, (and as regards mouse 2) 14th and 15th days larvae were found in the 
faeces. Mouse ( y) was killed on the 13th day. No larvae found in the lungs, 10 in 
the trachea, none in the mouth, stomach, or small intestine, 7 in the caecum, none 
in the colon. Mouse ( 2 ), killed on the 15th day, contained 2 larvae in the lungs, 10 
in the caecum. 
Thirteen mice (Mo to Am) died of cold or excessive infection; but 1 was 
examined. Larvae were found in the faeces of Ai on the 12th day. 
Mouse An received a dose of eggs 31 days old on November 18th. Larvae were 
found in the faeces on the 9th, 10th, 11th and 12th days thereafter, not on the 14th 
and 16th days. The mouse was killed on the 17th day. No Ascaris larvae were 
found in the trachea or large intestine. 
Mice Ao, Ap received doses of eggs 35 days old. Larvae were found in their 
faeces on the 9th and 12th days; they were killed on the 13th day. In Ao no larvae 
were found in the large intestine. In Ap three larvae were found in the caecum. 
Mice Aq, Ar received doses of eggs 37 days old. Ar died on the 1st day. Aq was 
killed on the 11th day. Larvae were found in the lungs, none in the large 
intestine. 
Mice Ms, At received doses of eggs 39 days old. They were killed on the 11th 
day. Nine larvae were found in the caecum of As. No examination was made of 
At, its entire large intestine being given to Pig 10. 
Mice Au, Av received doses of eggs 52 days old. They were killed on the 10th 
day. Six larvae were found in the tip of the caecum of An. The intestine of Av 
was given unopened to Pig 10. 
