2 70 ARACHNOIDEA. 



CASE it. It was his habit not to drink at his meals ; but in the night, 

 ^^^' growing thirsty, he often sipped some liquid out of a vessel made 

 of juniper wood. Inspecting this very narrowly, he observed 

 in the chinks between the ribs a white line, which, when viewed 

 under a lens, he found to consist of innumerable mites, precisely 

 the same with those that he had voided. Various experiments 

 were tried with them, and a preparation of rhubarb was found to 

 destroy them most effectually. He afterwards discovered them in 

 vessels containing acids, and often under the bung of casks. In 

 the instance here recorded, the dysentery or diarrhoea was thus 

 apparently produced by a species of mite, which Linnaeus thence 

 called Acarus dysenterise. 



Latreille thought it might be the cheese mite, or one of its 

 allies. It is against the probability of its being so that no re- 

 corded instance of this or any other mischief from cheese mites 

 has ever been recorded, although they are daily eaten in quan- 

 tities too great and too carelessly to leave a doubt that hundreds 

 of living individuals must be swallowed which escape the grinding 

 of our molars. If they did any harm there should be thousands 

 of cases of suffering from them in our medical works, but there 

 is none. 



No. 15. Tyroglyphus longior ( Gervais, in Walckenaer's Apter. iii. 1844), 

 (Acarus dimidiatus, Herm. ; Acarus horridus, Ttirpin ; Acarus Crossi, 

 of English writers). — 15. Magnified sketch of ditto, copied from Robin's 

 figures. 



Very easily distinguished from T. siro (with which it associates), 

 by its more rapid movements, larger size, longer and more cylind- 

 ric body, and longer and more shining hairs sticking out on 

 every side. Its habits, however, are very much the same, al- 

 though T. longior does not quite adopt all the partialities of T. 

 siro. It lives upon old and decaying cheese along with it, but 

 not equally on all; for instance, MM. Fumouse and Robin 

 mention that only one per cent, was found by them to belong to 



