SUPPLEMENT 705 



whole body ; the back and the face only remain free. The symptoms 

 consist in violent itching, the onset of which specially takes place 

 at night. 



The mite-tracks are fine curving lines, curved like a, u, c, or s, 

 which appear as if they had been scratched with a fine needle. Upon 

 closer examination with the magnifying glass one sees in their course 

 small openings. These openings, in persons who keep themselves 

 clean, are scarcely coloured ; but in patients whose occupations 

 necessitate their being associated with coloured or dirty substances, 

 they are dark. The length of the tracks varies from some millimetres to 

 i to 2 cm. They are at the one end, where the Sarcoptes is embedded 

 in the epidermis, widened like a funnel and slightly exfoliated. The 

 track at this point is sharply defined ; the mite shows through the 

 epidermis as a yellowish round point. In the course of the track there 

 develop papulae, vesicles or pustules, which raise the level of the track. 

 The intensity of these inflammatory appearances depends upon the 

 susceptibility of the human individual and upon the capability of 

 the reaction of the skin. There are people in whom scarcely 

 any inflammatory symptoms make their appearance ; on the other 

 hand there are some, especially children and lymphatic individuals, 

 in whom severe impetiginous ecthymatous pustules, together with 

 their sequelae, are set up. 



The results produced by scratching consist in papules, which 

 usually bear a small scab of blood, and are arranged in the form of 

 striae, in eczematous surfaces, weeping or sanguineous scabs, vesicles, 

 pustules, etc. The complications that set in are frequently urticaria 

 and even furuncles, lymphangitis and inflammation of the glands, 

 which now and then is followed by the formation of abscesses in the 

 glands. 



The duration of the disease is unlimited ; when untreated it leads 

 to a form of rare occurrence, that of scabies norvegica 1 ; in this the 

 collection of crusts and scales, in which a quantity of dead mites, 

 larvae and ova are present, may become colossal. 



The symptoms of scabies abate in the presence of intercurrent 

 acute diseases and reappear after the malady is over. The fact has 

 for long contributed to the idea of scabies being regarded as a disease 

 capable of being " driven in " upon the internal organs and forming 

 metastases. 



The diagnosis is rendered certain upon the discovery of a track. 

 Traces of scratching on the extremities and on the abdomen, papular 

 or pustular efflorescences between the fingers, toes, in the neighbour- 

 hood of the wrist, of the elbow, on the anterior border of the arm-pit, 

 on the tuber ischii, in the girdle region, and especially the presence of 



1 [This is produced by a distinct species, vide pp. 519-20. F. V. T.] 



