ACARUS SCAB1EI. 23 



meal-mite for this animal, and regarded it as a variety of the 

 cheese- arid meal-mite, as Acarus liumanus subcutaneus et scabiei 

 Geoffroy and De Geer regarded it as a distinct species ; Mor- 

 gagni, Fabricius (who saw it amongst the Greenlanders,) and 

 Wichmarm were very well acquainted with it ; but as it is diffi- 

 cult to find, it was for a long time forgotten, until at last the 

 Parisian student Gales, in 1812, was the occasion of attention 

 being again paid to it, by the famous substitution of the cheese- 

 mite for the true mite (' Essai sur le diagnostic de la Gale, sur 

 ses causes et consequences medicales et pratiques & deduire des 

 vraies notions de cette maladie/ Paris). His figures resemble 

 De Geer's figures of the cheese-mite. In 1834, following the 

 Corsican Renucci, Raspail at last succeeded in finding the true 

 mite and detecting the mistake of Gales, so that the renewed 

 knowledge of the mite dates from Raspail, although he could 

 not prevent Lareille from uniting the itch-mite and the cheese- 

 mite in Cuvier's f Regne Animal/ or Lamarck and Nitzsch from 

 expressing the opinion that two species of mites might perhaps 

 occur in the itch. Since this time the knowledge of the mite 

 has been gradually advanced, especially by Eichstadt, who was 

 not acquainted with the male, by Hebra and Gudden, also 

 through Kramer, of Gottingen, in 1846, who first distinguished 

 the male from the female, and later above all by Bourguignon, 

 who first gave a good description of the male, which was dis- 

 covered by Languetin. 



In this historical statement I have followed Martiny and my 

 own studies, but departed essentially from Gudden, who ascribes 

 Cestoni's letter to Bonomo, makes it to have been directed to 

 Redi instead of Vallisneri, and altogether sums up the history 

 very superficially in these words : " If we add thereto (Cestoi's 

 letter) from recent times, the works of Eichstadt and Hebra, 

 and perhaps also those of Bourguignon, we have got together 

 the best of the literature upon this subject/' In details I shall 

 follow the treatment and arrangement of the subject according 

 to Hebra, Schinzinger, and Gudden, with reference to my own 

 observations. 



Habitation of the mites and the mode of finding them. Even 

 Nyander says in his dissertation : " Acarus sub ipsa pustula 

 minime quserendus est, sed longius recessit ; sequendo rugam 

 cuticulae observatur; in ipsa pustula progeniem deposuit, quam 

 scalpendo offringimus et disseminamus, ita cogente natura." 

 According to Gudden we find the mites and their egg-passages 



