F. H. Stewart 
225 
The specimen was dead and somewhat degenerated. No lips are visible. The 
oesophagus resembles that of Ascaris lumbricoides larva. The intestine is loaded 
with black pigment granules. 
Text-fig. 6 should be compared with Text-fig. 5. It will be seen that there is a 
marked general resemblance. The reduction in breadth in the specimen from the 
stomach is pfcbably due to shrinkage after death and before fixation and to passage 
through alcohols. 
(6) From the rectum (Text-fig. 7). This specimen was also dead and was 
partially digested. In size and general appearance it strongly resembles the preceding. 
The head bears three well developed lips, one dorsal, two .subventral. The duct 
of the ventral gland is very clearly visible containing a deposit of haematoxylin. 
There can be little doubt that this is an Ascaris larva. 
Summary of Results. 
When eggs of Ascaris lumbricoides Lin. or A. suilla Duj. containing 
mature embryos gain entrance to the alimentary canal of the sewer 
rat, Mus decumanus, or the mouse, M. musculus, they hatch. It is 
not possible to say at present in what part of the alimentary canal 
hatching takes place. (The number of animals suitable for experiment 
at the disposal of the writer is unfortunately so small that he is unable 
to devote any of them to the working out of the details of the process.) 
A certain proportion of the larvae thus liberated escape in the faeces 
where imder suitable circumstances they can live for at least three 
days. It is, however, probable they ultimately succumb and that this 
is not a true road of development. t 
The majority of the larvae gain entrance into the body of the host. 
The exact point of entrance and the time after hatching at which 
entrance takes place have not been determined. Some animals show 
signs of illness on the second day after infection. The time elapsing 
between infection and the entrance of the larvae into the body is there¬ 
fore probably not more than two days. 
Larvae are found in the lungs and liver of the host not later than 
four days after infection and possibly as early as two days. Sections 
of the tissues show that they are situated in the air vesicles of the 
lung and in the blood capillaries of the liver close to the interlobular 
branches of the portal vein. 
Larvae are not found in the liver after the fifth day from infection. 
They are found in the bronchi about the seventh day and in the trachea 
on the eighth day. 
No larvae are found in any portion of the lung on the ninth day 
