928 Etiology. Patliogenesis. Symptoms. 



movement while yoiuig. When fully develoj^ed tliey become oval, 

 have a smooth capsule, inside of which a micropyle may some- 

 times be seen; they are somewhat larger than the Coccidium 

 oviforme. Nevertheless Liihe denies that the virus of the dis- 

 ease belongs to the coccidia, although he considers it as prob- 

 ably parasitic in nature. 



The mode of infection and the occurrence of conditions 

 influencing the disease are at present not fully known. 



Pathogenesis. According to Olt the disease process be- 

 gins in the cells of the sweat glands in which the coccidia appear 

 as brown granules, causing swelling of the glandular cells and 

 rapid proliferation of the contiguous cells. After the cells be- 

 come detached, they unite with colloid material which develops 

 through the action of the parasites, and with the secretion of 

 the sweat gland, forming a thickish mass. This mass stops up 

 the duct of the gland, which is changed into a small vesicle. 

 When the latter has reached a certain size, its attenuated wall 

 bursts and its contents are poured into the follicles of a neigh- 

 boring bristle and a larger vesicle develops from the original 

 one after coalescence with the considerably distended follicle. 



At first the vesicles situated in the cutis contain a serous 

 fluid and a few red and white blood cells ; later on they contain 

 a yellowish brown or quite black tallowy mass which may be 

 stratified and in which generally one or several very fine spirally 

 twisted bristles are imbedded which contain no marrow. These 

 are young and insufficiently developed bristles which have been 

 enclosed in the vesicle and are compelled to roll up in a spiral, 

 in the course of their further growth. 



Zseliokke explains the development of the vesicles in such a manner that tlie 

 epidermis plugs become elongated toward the cutis and growr into it, forcing aside 

 its cellular tissue and finally becoming cut off from the epidermis layer. Owing 

 to degeneration of the new formed cells, the foci, which are at first firm, are 

 changed into vesicles surrounded by a layer of epidermis. — Lungershausen believes 

 that the disease is due to a primary faulty development of the bristles which 

 cannot break through the epidermis but remain stuck in the hair follicle, whereupon 

 this is changed into a vesicle, after the outer root sheath has become detached from 

 the inner sheath. Siedamgrotzky, Johne and Ostertag consider the vesicles to be 

 small dermoid cysts; Kitt took tliem to lie athcromata. 



Symptoms. The eruption begins as a rule on the external 

 surface of the ears, on the croup, on the back, and also on the 

 external and internal surfaces of the thighs, vesicles of variable 

 size and exceedingly numerous being visible in the advanced 

 stage of the disease. The very small ones are pale yellow or 

 white and remind one of pearls by their dull luster; the larger 

 vesicles are of lentil to pea size, hard, lead gray, rust colored 

 or yellowish brown; later on they become violet, bluish red or 

 black, and are only slightly elevated above the surface of the 

 skin. In some places lentil-sized flat elevations may be seen, 

 each with a yellow, brown or black and undulating fine canal 

 which contains one or several bristles. Now and then such a 



