LEPTUS AUTUMNALIS. 67 



head. Emmerich never found passages, and their pe'sition was 

 generally at sm)h a small depth, that with a little practice they 

 could easily be removed with the finger-nail or a needle, and if 

 then put upon paper ran about briskly. Sometimes, also, the 

 animals are seen arranged in the form of a wreath or necklace, 

 or in masses and troops. The time of their parasitic existence 

 does not last long. This mite is usually found upon man only 

 in July and the beginning of August ; subsequently it probably 

 goes into the moss on the ground, to pass through its further 

 development there in quiet. For this reason Jahn was unable 

 to send me specimens of these parasites in September. But I 

 am none the less grateful to him and Emmerich for the kindness 

 with which they furnished me with information upon this para- 

 site, which I have hitherto sought for in vain in this place. 



During harvest the mite bores, of ten in immense numbers, into 

 the skin of the reapers, and, indeed, in the neighbourhood of the 

 roots of the hairs, producing troublesome itching, inflammation, 

 swelling, and even fever. On account of the red colour of the 

 mite, the complaint has been denominated " Rouget." 



According to Jahn and Emmerich, the mite which I have 

 figured upon Plate IX, fig. 8, agrees with that observed by them ; 

 except that the eyes are wanting, as the drawing, for which I 

 am indebted to the kindness of Professor Leuckart, represents 

 the mite from the ventral surface. However, there is a figure 

 of the mite in Wiegmann. 



According to Jahn and Emmerich, the mite rarely lives very 

 long as a parasite upon the human skin ; even a few days' resi- 

 dence is a rarity. But when peculiarly unfavorable external 

 circumstances are in action, and the patients are constantly pass- 

 ing by those places where the mite is abundant, as, for instance, 

 the gooseberry gardens, the disorder may last for several weeks 

 and months, by the chain of consecutive relapses, but never over 

 the time of harvest. 



Diagnosis. The discovery of the mite upon the body is ren- 

 dered easy by the colour of the animal. It can then be 

 taken out of the centre of the swelling with the point of a 

 needle. To collect them from the gooseberry bushes, it is 

 only necessary to lay a sheet of white paper under the bushes 

 upon which the animal is common, and then beat the bushes. 



Therapeutics. The avoidance of the places infested by the mites 

 is sufficient ; according to Jahn, washing with soap and water, 



