HYFOFIDJE: 237 



For nearly twenty years the above conclusion was accepted by 

 the scientific world as the true account of the development of 

 these Acarids; but in 1868, M. Claparbde published the result of 

 his observations on them, which led him to challenge the sound- 

 ness of Dujardin's view. Claparede found his observations correct 

 to a certain extent, but carried them further, and drew different 

 conclusions. To begin with, he objected that the Hypopus form 

 is eight-footed, which is against its being a larval form; for, as 

 the reader knows, the larvae of all known Acari appear at first 

 with six feet. Then he took exception to the idea of its being 

 produced from an egg with feet, remarking, with reason, that the 

 exceptional included form had much more analogy with the 

 nymph or pupa stage of other insects. Passing these, which are 

 only theoretical objections, M. Claparede next took a stronger 

 objection, founded on actual observation of the development of 

 the Gamasidse from the tgg. Dujardin had not traced this, but 

 Claparede had, and found that the Gamasus left the Qgg as a six- 

 footed larva, which already possesses the main characteristics of 

 the mature animal, and in no respect shows any resemblance to 

 Hypopus. He adds, " This objection of mine I will later, I hope, 

 confirm in a treatise upon Gamasidae;" but, unhappily, his la- 

 mented death occurred before he had done so. The observations 

 that he does record are the following. He says that in the neigh- 

 bourhood of Geneva an Acarus is met with in great numbers, which 

 multiplies itself, in vegetable substances, in great quantities, as in 

 hyacinth bulbs, potato and dahHa roots, half-rotten cabbage -stalks, 

 etc. It was new, but he determined it to be closely alHed to the 

 species Tyroglyphus siculus of Robin and Fumouse, and the Tyro- 

 glyphus entomophagus of Laboulbene, and described and figured 

 it under the name of Tyroglyphus Dujardinii. He set himself to 

 study this species, and presently he was struck by the remark- 

 able fact that he could find nothing but females. He examined 

 hundreds and hundreds of individuals without coming across a 

 single male. He was hence inclined to think that he had to do 



