40 
Ascaris lumbricoides 
(B) Experiment in which A. suilla larvae in the faeces of mice were 
administered to two pigs. 
Ripe eggs of A. suilla were administered to eight mice. The faeces dropped by the mice 
on the 12th and 13th days after infection were collected, and found to contain immobile 
Ascaris larvae. After an interval of 14 days the faeces were administered to two sucking 
pigs three days old. The pigs were killed three days thereafter, and no worms were found in 
their intestines. 
The experiment was therefore negative, but taking the technical difficulties 
into consideration, it would require to be repeated several times to establish 
with certainty that the larvae passed in the faeces of mice are non-infective. 
III. The anatomy of the larvae of A. Suilla Duj. found on the 
19th day after hatching in the small intestine of the pig. 
Size. Length while alive 7 mm., when fixed in 70 percent, alcohol 6-5 mm. 
Maximum breadth in alcohol 0-15 mm. Head (Fig. 1). 0-04 mm. long, lips 
connected at their bases by membrane, papillae as in the adult, no teeth, 
head separated from the body by a shallow circular groove. Body. Surface 
markings (1) annuli as in the adult, 0-005 mm. broad, (2) longitudinal ridges 
(Fig. 3) 30 to 32 in each (dorsal and ventral) half, ridges not continuous from 
one annulus to another nor in the same longitudinal line in successive annuli. 
Anus situate 0-2 mm. from the tip of the tail. Tail. As in the larva of the 14th 
day after hatching. Cuticle (Fig. 2). Consists of three layers, the mid-layer 
stains deeply with iron haematoxylin. 
Lateral membranes (Figs. 2 and 4) extend from the neck nearly to the tip 
of the tail, are formed of all three layers of the cuticle, the mid-layer gives 
rise to the tri-radiate skeleton, the inner layer covers the lateral line and 
partly fills the triangular space underlying the skeleton with irregular lamellae. 
Lateral lines (Fig. 3) divided as in the adult by two very fine horizontal septa. 
The lateral canals are attached to their inner surfaces— vide infra. 
Alimentary Canal. Mouth triangular in transverse section, funnel-shaped. 
Oesophagus 0-7 mm. long, simple club-shaped, slightly expanded also at 
anterior extremity; cuticular lining and outer membrane very fine; radial 
muscles well developed, embedded in a stroma of protoplasm, oval nuclei 
present in this stroma, number in front of nerve ring—in dorsal segment 5, 
in sub ventral segments 4 each; behind nerve ring—in dorsal segment 5, in 
left sub ventral 4, in right sub ventral 5; the posterior end of the dorsal seg¬ 
ment contains the body of a large nucleus, which extends across the entire 
segment, and sends two branches forward along the upper edges of the sub¬ 
dorsal radii, and two branches downward and forward into the subventral 
segments. 
Nerve ring. 0-182 mm. from the anterior extremity, contains one nucleus 
opposite each lateral line and each subventral muscle field. 
