Louping-ill in Sheep. 
557 
were present in connexion with the respiratory organs, and it is 
therefore probable that the inhaled air was not the carrier of the 
infection. The possibility of infection by means of germs taken in 
with the food or water cannot be so certainly excluded, for although 
no abscesses were discovered in connexion with the alimentary 
tube, some were present in the liven 
Both in England and in Scotland, there is in louping-ill districts 
a very general belief among farmers and shepherds that ticks are 
somehow concerned in the production of the disease, and, assuming 
what I shall subsequently show to be probable, viz., that the germs 
which are responsible for the formation of the abscesses are soil 
organisms, it is not by any means a far-fetched idea that ticks may 
sometimes be the instruments of infection. Indeed, Case I., in which 
the pus that had formed around the point of attachment of the 
tick to the skin contained a bacillus morphologically similar to 
that present in the spinal abscess, is strongly suggestive of this 
view. 
Infection by means of the umbilicus or navel is a comparatively 
common occuri’ence in the young of all the domesticated animals, 
but this method of infection is usually easy of detection at the 'post- 
mortem, owing to the presence of suppuration or some other form 
of inflammation at the navel itself, or along the course of the vessels 
that pass backwards and forwards from it inside the body. As pre- 
viously stated, special attention was given to these parts in all the 
lambs examined, but in every case the navel was perfectly healed 
up, and its vessels appeared quite normal. 
Coming next to discuss the probable habit of life of the germs 
concerned in louping-ill, it would be all-important if one could state 
whether they belong to the class of obligatory, or to that of 
facultative, parasites — to know, in other words, whether pysemic 
meningitis is a contagious disease or not, for, be it observed, there 
are many germ diseases, such as tetanus, actinomycosis, and black- 
quarter, that are neither contagious nor infectious in the ordinary 
sense of these words. These are the diseases whose germs ordinarily 
live and propagate outside the animal body in soil or water, and are 
only occasionally, and in a manner accidentally, the cause of disease, 
while the strictly contagious diseases, such as glanders and swine 
fever, are caused by germs which in natural circumstances never 
propagate except in the bodies of animals. 
There need be no hesitation in venturing the opinion that none 
of the forms of louping-ill is contagious. The fact that the 
disease is only met with in the spring months, and that it is not 
already diffused over the whole country, but is still obstinately 
attached to particular districts, and even to particular tracts of 
unfenced moor or hill, is wholly inconsistent with the view that 
contagion plays any part in its development. The only assumption 
that is in keeping with the known facts regarding the occurrence of 
the disease (pysemic meningitis) is that it is caused by germs that 
are normal inhabitants of the soil. It is probable that there are 
• certain districts in which these germs are present at all seasons of 
