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Parasites of Mange. 

 The mange parasites belong to the genus Acarina, and are known 

 to exist on the horses in three species, namely : — 



(1) Sarcoptes. 



(2) Dermatocoptes. 



(3) Dermatopbagus. 



They are very minute creatures, and can only be properly recognized 

 by the microscope ; by the naked eye they are just, seen as a very 

 small speck. Under the microscope the male can be distinguished 

 from the female. 



In the abdomen of the latter, eggs of a relatively large size may be 

 seen — a female can deposit from 15 to 25 of these. 



The hatching period lasts from three to seven days. The young 

 acarinae, called larvae, then leave the egg. 



They move about on three pairs of legs ; on reaching the state of 

 nymphae they have four pairs of legs ; and from that stage in a fort- 

 night's time they become mature. 



Eate of Increase. 



The following calculation may show in what an alarming proportion 

 the descendants of a single Sarcoptes female can increase. Let us 

 suppose that one mature female produces ten young females and five 

 young males, these produce a fortnight later the same number, viz., a 

 {Sarcoptes grandmotber has after a lapse of 30 days fully 150 offsprings. 

 These will produce after 30 days some 10,000 descendants, and in 

 three months we arrive, following the same proportion, at the enor- 

 mous number of over one million Acarinae. 



This may sufficiently explain how quickly the disease can spread, 

 and, when neglected, how soon a number of animals can be found in a 

 very short time to be affected by the disease. 



Difficult to Destroy. 



These Acarinae are very tough parasites, and not always easily 

 destroyed. In moist places, amongst manure, for instance, they can 

 live as long as eight weeks ; in dry surroundin2;8 from two to six 

 weeks. Eggs of Acarinae in similar conditions live respectively two 

 to four weeks and four to six days. 



This shows that any place occupied by a horse suffering from mange 

 may remain infected for a considerable time. 



The three different species of Acarinae above mentioned do not 

 exist at all in the same conditions, but their results are practically the 

 same. 



According to the seat of the disease, the mange can sometimes be 

 recognised without the help of the microscope. 



Sarcoptes Mange. 



The Sarcoptes dig real tunnels in the skin.andlay their eggs there ; 

 these, as they develop, go on with the digging process, and in so doing 

 cause a severe inflammation of the skin. 



This is especially noticeable on the head, neck, and shoulders of the 

 animal, which are the first to be affected, but the disease may start on 

 any part of the body. 



The first symptoms are small spots devoid of hair ; these increase 

 in circumference, and very soon join each other. In these spots can 



