328 BOARD OF AGRICULTURE. 
semitransparent spherical nodules contain the younger worms, 
often microscopic, and without sexual development, while 
the larger and dark colored cysts contain worms of nearly 
their full size, and furnished with sexual organs. Some of 
the larger cysts are not spherical, but irregular in outline, 
and these, on being opened, are found to contain the debris of 
the parent worm with numerous ova and microscopic embryos, 
mixed up with an abundance of pus cells, granular masses 
and granules. At times, more or less of the worms approach- 
ing maturity may be seen making their way through 
the mucous membrane from the pulmonary cysts to the 
bronchial tubes. 
The second stage of their existence, and that in which they 
are most injurious to their hosts, is that of the sexually ma- 
ture parasite in the bronchial tubes. They may be found at 
all points from the throat down the windpipe and through the 
smallest ramifications of the air tubes, either singly imbed- 
ded in the frothy mucous, or in large numbers rolled into 
pellets, and it may be, completely obstructing the bronchial 
tubes. The mucous membrane of these tubes is reddened, 
softened, and inflamed, and the smaller tubes that have har- 
bored the worms for some time are usually dilated much be- 
yond their natural size. Many thousands of these worms of- 
ten exist in the lungs of a single animal, and as one worm 
will produce its thousands of eggs, capable of contaminating 
a large herd, their presence in any particular stock ought not 
to be lightly passed over. 
Colin, who has investigated this subject very thoroughly, 
says: ‘The strongyli of the calf remain in the vesicular tu- 
mors a much shorter time than those of the sheep. They 
are encysted and quiescent but for a short period and spend 
most of their life in the bronchia, where they accumulate in 
masses which intercept the passage of air through many of 
these tubes and produce an intense dyspnoea, or even slow but 
fatal asphyxia, the lung tissue meanwhile containing marked 
traces of the passage of the parasite. There are cases where 
the bronchia in the lungs of the calf are so invaded that the 
lobules furthest from the larger bronchial tubes are denied 
