270 Transactions. — Zoology. 



Positive proof of the species infesting the skin can only be ascertained 

 by those having opportunities of searching for them at the proper time, 

 when this pseudo-scab is prevalent. 



The lung -worm in sheep. 



The result of an examination of a portion of a sheep's lung forwarded 

 by the Stock Department is as follows: — The sheep was depastured at 

 Marton and was killed in June last. Near the opening of the bronchial 

 tube was found a contorted heap of filiform white worms, which, on exami- 

 nation, proved to be a species of Strongylus. All the specimens examined of 

 this travelling detachment, were found to be packed with eggs, each egg 

 showing under the microscope a coiled embryo within, in an advanced stage 

 of development ; a large portion of the lung structure was found to be per- 

 fectly healthy, and evidently had not been visited by the worm, but in the 

 remaining portion some worms were found which proved under the micro- 

 scope to be nearly filled with eggs, none of which, however, showed any 

 traces of an embryo, thus no doubt explaining their delay in moving with 

 the others ; male worms were also found here. This portion of the lung 

 proved to be in a diseased state, being flabby and white, the worms having 

 evidently burrowed through its body and formed a lodgment there till they 

 should arrive at their normal size and become fertile with ova. It appears 

 that they remain in the lung till the embryos reach the mature stage of 

 bursting their envelopes, when the parent worms commence to evacuate 

 their temporary abode and move towards the damp ground, where they find 

 the conditions best adapted for the first stage of life of the young worms, 

 and where the parents no doubt die. 



It is at this travelling stage that the worms become most dangerous to 

 their host, in proportion to theu' numbers, filling the air passages of the 

 lungs and nostrils, and often when numerous in weak sheep or lambs 

 causing suffocation. The life-history of this nematode clearly shows that 

 it only occupies the lungs of sheep for a few weeks during summer ; leaving 

 the ground in spring while yet in an immature condition and scarcely 

 visible to the unassisted eye, and crawling up the nostrils of the sheep, they 

 reach the lungs without causing much annoyance. The period of escape 

 by the same track in autumn, after they have reached their mature con- 

 dition and become fertile with embryotic ova, may extend over several days, 

 during which time the sheep labour under great annoyance, and if the 

 worms are numerous are in much danger of suffocation ; as they advance 

 towards the nostrils in contorted balls and fiU up the air passages, if not 

 speedily expelled the sheep must die. From what has been said it is 

 shown that the maturity of the embryo occurs in some worms earlier than in 

 others, thus lengthening the period of annoyance although diminishing the 

 danger of suffocation, as the worms are not all travelling at one time. 



