386 Ascaris lumbricoides, L. 
active embryos. Doses of eggs from the same cultures were administered to 
three young white rats as a control on two successive days. The rats were 
killed on the 7th and 9th days after the first dose, when a considerable number 
of active Ascaris larvae were found in their lungs. On the 8th day after 
treatment both the sucking pigs showed signs of pneumonia. They were 
breathing at the rate of 140 per minute, and the temperature of one was 
raised half a degree above the normal. 
1. The first sucking pig was killed on the 14th day. No Ascaris larvae 
were found in the trachea, or in a fragment of the lung. Numerous larvae 
were found, however, in the small intestine, caecum and rectum. Measure¬ 
ments as follows from specimens fresh in salt solution: 
Small intestine 2*5, 2-72, 3-04, 3*20, 3*80 mm. 
Caecum 2-96, 3*04 mm. 
Rectum 2-4, 2-48, 2*9 mm. 
2. The second sucking pig was killed on the 19th day after infection. 
The stomach, small intestine, caecum and colon were opened, the mucous 
membrane scraped and washed, and the washings sedimented and examined 
under a dissecting microscope. No larvae were found. The muscular and 
serous coats were not specially examined owing to lack of time. 
3. A pig aged two months was found to be passing Ascaris eggs in the 
faeces. It was treated with Santonin, and four days thereafter its faeces 
did not contain eggs. When it was 2J months old about 50,000 ripe Ascaris 
eggs, one month old, were administered to it. Eggs from the same cultures 
were administered to three old white rats, which had previously been subjected 
to Ascaris infection. When these were killed, on the 7th day, one Ascaris 
larva only was found in their lungs. The pig was killed 31 days after infection. 
No worms were found in its intestine. 
Anatomy of the larva of Ascaris suilla from the intestine of the fig fourteen 
days after infection. 
The measurements of the total length of fresh specimens is given above. 
For the general outline see PI. XX, fig. 1. The head (figs. 2 and 3) bears three 
lips with the four papillae characteristic of the adult. The internal surface of 
each lip is lined by thickened cuticle, and is grooved longitudinally (fig. 3). 
Each lip is furnished with a muscular bundle continuous with the muscular 
body of the oesophagus (fig. 2, mus.). 
The cuticle of the body surface is marked by a series of rings 0*004 mm. 
in breadth (fig. 3). In sections stained with iron haematoxylin it is not darkly 
stained, and is therefore not markedly cuticularised. Each lateral line bears 
a lateral membrane extending nearly from the head to the tail, and supported 
by a firm triradiate cuticular skeleton (figs. 5 and 6), the basal plates of 
which are embedded somewhat deeply in the substance of the lateral lines. 
The muscular system shows a distinct advance in development when 
compared with that of the larvae from the trachea of the mouse. The nerve 
