588 DISEASES OF THE SKIN. 



skin and mucous membranes with bites. Anxious and crazed^ 

 their victims run away or throw themselves upon the ground 

 moaning ; many perish on account of the inflammation and obliter- 

 ation of the bronchi. Those which resist show serious symptoms ; 

 the skin becomes covered with a large number of small pimples 

 which are hard and painful, the mucous membranes are inflamed ; 

 the inflammatory phenomena persist often for from three to four 

 weeks. On animals which succumb we find a sero-sanguinolent 

 infiltration of the subcutaneous connective tissue, also an inflam- 

 mation of the exposed mucous membranes ; finally, hyperemia and 

 œdema of the lung. When the simulia have penetrated into the 

 pharynx, larynx, and trachea, the mucous membrane of these 

 canals is much tumefied; the respiratory tract is sometimes entirely 

 obstructed. The treatment consists in making cold-water lotions 

 upon the skin, and in practising scarifications upon the accessible 

 regions of the inflamed mucous membranes. As a prophylactic, 

 lotions of tobacco lye have been recommended ; we may also use 

 cresol, carbolic acid, tar, asafoetida, or a decoction of walnut leaves 

 in vinegar. 



2. Hypoderma of the ox (Œstrus or Hypoderma bovis). 

 This fly produces in this animal, sometimes also in the horse, the 

 donkey, and the sheep, nodes which are ordinarily observed upon 

 the shoulders, back, lumbar, croup, and thorax. The eggs of the 

 hypoderma, deposited upon the skin, give birth to larvae which per- 

 forate this membrane and become lodged in the subcutaneous con- 

 nective tissue, where they remain for about nine months (from July 

 to March). While their development is going on they irritate the 

 neighboring tissues, which become inflamed and infiltrated with pus^ 

 and form tumors which may reach the size of a pigeon's egg. 

 When the larva has reached the adult state it leaves its connective 

 tissue covering and escapes ; dilating, by means of the posterior 

 part of its body, the cutaneous opening which it has made. These 

 parasites are not generally numerous, but we find at times from 

 fifty to one hundred ; then they may occasion serious trouble : the 

 animals become emaciated, now and again they are under the influ- 

 ence of an intense excitement ; when at pasture they go through 

 uncontrollable movements, toss the tail, bellow, run toward water, 

 and try to enter the stable. The treatment consists in securing 

 the removal of the ripe larvse by compressing the tumors, or in 

 incising these by means of a bistoury. As prophylactic means, we 



