others which are referred to by authors as of occasional occurrence. These 

 have not been observed by veterinarians in this country, aud do not appear to 

 be of sufficient importance to require any special notice. 



The different round worms have been described separately, but it is necessary 

 to observe that the host may harbour more than one species at the same time. 

 An extraordinary case is reported by Krause of a horse which was infested 

 with 500 Ascaris megalocephala, 190 Oxyuris curvicula, 214 Sclerostoma 

 armatum, and an immense number of Sclerostoma tetracanthum, in addition 

 to some cestode worms, both mature and in the scolex stage. 



Such a state of parasitism must be taken as altogether out of the common 

 course, and it is unfortnnate that there is no record of the animal's condition 

 during life. 



Occasionally the respiratory tubes of the horse are invaded by a nematode 

 worm, Strongylus micrurus. This form of parasitism is, however, rare ; 

 indeed, only occurs when colts are grazing on pastures on which there are 

 calves and lambs infested with strongles, and the parasites will be referred to 

 in their proper place as they exist in the respiratory organs of ruminants. 



NEMATODE WORMS IN CATTLE AND SHEEP. Ruminating animals 

 habitually harbour several varieties of round worms, some of which cause 

 serious derangement. Of chief importance among them is the worm which 

 invades the breathing tubes and lung tissues, inducing changes of structure 

 which remain long after the worms have migrated from their habitat. The 

 lung strongle, or lung worm, is well known to the stockowner, presenting the 

 appearance of a piece of thick white cotton, from 1^ in. to 3 in. in length, 

 filling up the smaller tubes like masses of tangled thread, and sometimes 

 existing in the windpipe and even in the nasal chamber, to which they wander 

 or are driven by the forcible respiratory efforts consequence on the act of 

 coughing. 



Strongles in the lungs excite irritation, which is reflectd to the larynx, and 

 coughing is the result, hence the common name, husk or hoose, which is given 

 to the disease. Constitutional derangement follows quickly on the invasion of 

 the parasites, and loss of condition, increasing to a state of emaciation, is the 

 natural consequence. 



Losses among calves and lambs from the ravages of the lung worm are some- 

 times very extensive, and the stockowner may be puzzled to account for them. 

 The mere presence of a number of thread worms in the respiratory tubes does 

 not seem to be a sufficient explanation. 



In the first place, it must be understood that the mechanical blocking up of 

 the smaller air tubes by the accumulated worms interferes with the proper aera- 

 tion of the blood. Next, the irritation of the mucous membrane, which is 

 indicated by incessant coughing, is very exhausting ; and, further, there is a direct 

 loss of food due to the inability of the young animal to feed while coughing, and 

 the diminished desire for food which is incidental to the state of general 

 debility. Many years ago the subject of the lung worm attracted the attention 

 of stock breeders, who are the greatest sufferers, and prizes were offered for 

 essays in the life history of the worm, and the means of cure and prevention. 

 Under this stimulus some valuable papers were produced, but the main point 

 was never reached, i.e., a knowledge of the different phases in the development 

 of the lung worm, sufficiently accurate to enable the observer to prevent its 

 ravages ; and up to the present time there are some steps in the progress of the 

 embryo towards maturity which have not been traced. 



