534 



DISEASES OF THE SKIN. 



alies of pigmentation ; some are of a surgical order : warts, cutaneous 

 horns, elephantiasis, ichthyosis, phlegmons, erysipelas, etc. 



Sebaceous pimples (Talgkndtchen) constitute a morbid variety, of 

 which we must say a few words. They are the result of the ob- 

 struction of the excretory canal and of the sebaceous glands, and 

 of the distention of these latter by secreted matter ; these are phe- 

 nomena which are accompanied by inflammation of the neighboring 

 cutaneous tissue. They are identical with acne in man ; they are 

 firm, and from the size of a lentil to that of a pea. In compress- 

 ing these a pasty matter is forced out which is similar to boiled 

 gruel. Later the papules are transformed into furuncles. In the 

 horse they are found on the neck, shoulders, and back ; in fine 

 breeds of sheep they may be found on the inner surface of the 

 thighs (Negretti) and on the lower abdominal wall (Haubner). 

 Some of the eruptions formerly described under the name of 

 tuberculous eruption seem as if they ought to be classified in this 

 group. In the dog, besides exanthema of typical acne, which is 

 produced by Demodex folliculorum (see Follicular Mange), we find 

 frequently a furunculosis of the median part of the nose produced 

 by prolonged irritation of the muzzle; it is very tenacious and only 

 yields to incisions.^ 



II. SKIN DISEASES CAUSED BY VEGETABLE 

 PARASITES. 



DBRMATOMYCOSBS. 



Among the skin diseases of vegeto-parasitic origin, three only 

 are well known in our animals, namely, depilating thrush (herpes 

 tonsurans), favous thrush (favus) and contagious pustulous dermatitis 



1 Some rare observations have been related concerning cutaneous tumors of a 

 mycotic nature. In a cow Mollereau has observed on the left side of the upper part 

 of the neck an actinomycotic tumor measuring twenty centimetres in diameter; this 

 was hollowed by a fistulous passage from which flowed a thick white pus, in which 

 the microscope showed numerous actinomycetes. The Botryomycotic neoformations 

 remarked in the horse by Perroncito and Soula aflected mainly the subcutaneous 

 tissues. We find in chickens and pigeons a cutaneous trouble which consists of more 

 or less numerous nodules of a round or oblong shape and of yellowish color, their 

 volume varying from a poppy-seed to that of a grain of corn. The largest are found 

 on the base and commissures of the bill, on the nostrils, and under ths nasal mucoua 

 membrane, also around the external auditory meatus, upon the border of the eyelids 

 and the face. They form yellowish rugosities upon the comb and small barbel of 



