374 ME. A. D. MICHAEL ON HTPOPI, 



Fiirstenberg's Somopus, wbicli lie declares to be wrongly de- 

 scribed, and to be an ordinary Hypopus. 



Claparede's suggestion tbat Hypopus was tbe male of Tyro- 

 glyplius was practically disproved before he made it, for, while 

 Claparede was studying tbis Tyroglyplms, be was not aware that 

 Professor C. Eobin and Dr. Fumose were doing tbe same thing ; 

 they published their paper* shortly before Claparede's. They 

 called the species T. echinopsis, which name must stand. They 

 did not deal with Hypopus, whicb they apparently did not trace 

 as being connected with the life-history, but they did find the 

 iinquestionable male of the species. 



P. Megnin took up the subject in 1873, first in his memoir 

 upon Tyroglyphus rostro-serratusf, and afterwards in his memoir 

 on HypopusX ; and his labours were rewarded by tlie Prencb 

 Academie des Sciences witb the Thore Prize of 1873. His may be 

 said to be the present theory. 



Megnin experimented upon Tyroglyplms rostro-serratus and 

 T. mycopliagus, botb of them species found by him in immense 

 quantities on mushrooms {Agaricus campestris) ; he bred Ids 

 creatures in cases, supplying them with pieces of fresh mush- 

 room from time to time. He found that when the musbrooms and 

 cages got dry, his Tyroglyplii disappeared, and were replaced by 

 swarms of Hypopi ; when moisture was added, the Hypopi disap- 

 peared, and the Tyroglyphi were again in great quantities. Spe- 

 cimens which he kept in separate cells appeared to be almost 

 inert, and adhered motionless to the side of the cell, but when 

 moiskire was added, these Hypopi turned into nymphs of Tyro- 

 glypJius. The construction which Megnin put upon these facts 

 is, that Hypopus is a form into which nymphs of Tyroglyphus 

 change, when, through dryness of the atmosphere, or other 

 causes, there is a difficulty in their continuing to live as Tyro- 

 glypJii, and that it is a provision of nature to insure the preserva- 

 tion of the species, by carrying it over periods of drought, &c. ; 

 he also saw the iZj/pqpzfs inside the nymph of Tyroglyplms ]\x&t 

 before the ecdysis, as Claparede had done. 



Megnin also attacks Piirstenberg — declares that the latter's 

 mouth-organs were pure fancy, and speaks very strongly against 



* Journ. de I'Anat. et de la Physiol. (Eobin's), 1868, No. 3 (May and June). 

 t Comptes Eendiis Acad. Sc. Nat. 1873, 2<= ser. pp. 129 and 493; Journ. 

 de I'Anat. et de la Physiol. (Eobin's), t. ix. p. 869 (1873). 

 X Ibid. t. X. p. 226 (1874). 



