282 Miscellaneous. 
Complete Biological Evolution of the Elm-tree Aphis (Tetraneura 
ulmi, Aut.). By M. J. Licnrensrum. 
For several years past I have communicated to the Academy some 
new views concerning the biological evolution of the Aphides. These 
views have been rejected by some entomologists and received with 
favour by others. Amongst the latter, Prof. Kessler, of Cassel, 
has done me the honour of placing “ Confirmation of the Lichten- 
stein Theory’ as a subtitle to the last observations which he has 
published on the Aphides of the cornel and apple-tree (Aphis 
lanigera). 
Another entomologist, Prof. G. Horvath, Director of the Phyl- 
loxera station in Hungary, observed, in the autumn of 1882, that 
the Aphides which live during the summer at the roots of the 
maize became winged and repaired to the trunks of the elm trees, 
upon which they deposited individuals wanting rostra and sexual. 
Believing, from the nature of the plant attacked, that he had to do 
with the Aphis of the maize-root (Pemphigus zee-maydis, Léon 
Dufour, according to Lon), he published, in a French entomological 
Review, the interesting fact which he had observed, concluding thus : 
—‘“ The Pemphigus of the maize- pros migrates from its subterranean 
habitat to the trunks of elm trees ; but I donot know what becomes 
of it afterwards.” 
On this information I had to try to obtain a counter-proof. As 
the elm, here as in Hungary, only nourishes one species of Pem- 
phigus (P. pallidus, Haliday, sub Eriosoma), [had no doubt that by 
taking this species as it emerged from the gall, and forcing it to 
deposit its eggs upon the maize, I should obtain the subterranean 
phase observed by Horvath. 
I met with complete failure, however; not one of the thousand 
little Pemphigi which I placed upon the maize-roots attached itself. 
I had, nevertheless, carried on my experiments with the greatest 
care, by growing the maize in glass vessels, which permitted me to 
observe with the lens the roots pressed against the transparent sides 
of the vessel. 
I was greatly disappointed; but as I had my arrangements 
ready, I extended the experiments to the other species which live 
on the elm; these are four in number—two Schizoneure, ulmi and 
lanuginosa ; two Tetraneure, rubra and wlmi. The first three 
species died, like the Pemphigus, without attaching themselves to the 
roots of the maize ; but, to my great satisfaction, I saw the larvee of 
the fourth species, Tetraneura ulmi, attach themselves and rapidly 
increase in size, covering themselves with the woolly or cottony 
secretion so common among this group of insects. I wrote im- 
mediately to M. Horvath, ‘ The counter- -proof of your discovery did 
not ‘succeed with me as regards the Pemphigus of theelm. Are you 
sure that you are not mistaken? Send me the winged insect which 
migrates: from the maize-roots to the elm.” 
Thanks to the method of preservation which I had invented for 
the transimission of Aphides in a drop of Canada-balsam, between 
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