A, e. OlDEMAN.s, XüTKS ON ACARI. 73 



by VON Siebold, 1850, and Phytoptus (corr. Phytocoptes) by 

 DujARDiN, 1851. This larva distinctly bears eggs in its body, 

 which are laid and, hatching, give rise to similar larves. 

 At the end of summer these larvae eukyst. In the beginning 

 of spring the kyst burst ae<niatorially and a hexapod larva is 

 born »qui suivant les phases des larves hexapodes des Tétra- 

 nyques ordinaires, se développe et donne naissance à l'adulte 

 sexué chargé de recommencer le cycle.« 



If DoNNADiKu's observations were exact, we should have here 

 a case of p a e d o g e n e s i s. 



How inaccurate the observations of Donnadieu were may 

 be proved — if this still is necessary after all what I have 

 related above — by the following phrase : speaking of the 

 hexapod larva of Tdronycltas he tells us: »Après plusieurs 

 mues qui permettent ii I'Acarien de grossir, on voit apparaître, 

 sur la peau de la larve hexapode, en arrière des pattes pos- 

 térieures, deux bourgeons qui se développent et deviennent la 

 quatrième paire de pattes.« — Commentary superfluous!!! 



Alas for Donnadiel", but fortunately for science subsequent 

 observers have shown that Tetronychiin does not show in its 

 development any stage resembling EriopJiyes, and this on its 

 turn does not pass through a Tetiviiychus-stage, or in other 

 terms Donnadieu has wrongly observed and still more wrongly 

 concluded ! There is no parthenogenesis in l'etroìiycìiidae, nor 

 in Eriophyiilne, or at least hitherto it has not been proved 

 incontestably by breeding. 



In 186G Richard Beck published a paper entitled »A short 

 description of an a car us and its agamic repro- 

 duction « in the T r a r s a c t i o n s o f t h e Microscop- 

 ical Society, New Series, vol. 14, p. 30 - 34 and in T h e 

 Zoologist, New Series, vol. I, p. 236 - 240. Here he commun- 

 icates us his results of breeding. The species, accidentally 

 kept by him alive to follow its mode of reproduction, was 



