32 The Scottish Naturalist. 



''After having studied Dr Adler's papers, I remembered di- 

 rectly some similar facts given by Mr Lichtenstein in Stettin. 

 Entom. Zeit, 1877, on the Hemipterous genus Phylloxera; the 

 alternation is here very remarkable. The bisexual form origi- 

 nates from pupae, which are produced by larger-winged forms, 

 which possess no external sexual organs, and can therefore not 

 copulate. j\Ir Lichtenstein calls this form of propagation antho- 

 genesis. A certain similiarity with Cynips consists in the fact 

 that the different forms of Phylloxera emigrate in spring and re- 

 turn in the fall. So the well-known Ph. vastatrix emigrates from 

 the leaves to the root of the same plant, and needs therefore no 

 special winged forms for the purpose of emigration. But Ph. 

 qiiercus changes to another tree, and needs therefore two winged 

 forms, which are different one from the other. One partheno- 

 genetic form brings the summer colonies from Ilex to Pobur, and 

 another anthogenetic fall form brings them back from Rohir to 

 Ilex. The fact that some species possess two different winged 

 forms will probably reduce the number of the described winged 

 species. Till now it is only known that Ph. Iichte?isteinii is the 

 anthogenetic form of Ph. quercus, and Ph. Signoretii probably 

 the same form of Ph. flo7'e7itijia. Mr Lichtenstein presumes that 

 many Pemphigus and Adelges will possess similar forms, and ob- 

 servations made by myself on one species in the last year seem 

 to favour his opinion. 



" Such alternations stated without doubt for Hymenoptera and 

 some Hemiptera, and probable by analogy for some Diptera, 

 will certainly not fail to occur in other orders, and are probable 

 in some Lepidoptera heterocera. 



" A paper by Mr P. Cameron, in the ' Scottish Naturalist ' for 

 October 1877, the substance of which is incorporated and fully 

 approved in the President's Address to the Entomological Society 

 of London, arrives at conclusions entirely unfavourable to Dr 

 Adler's memoir. To corroborate my views about the memoir I 

 wish to give a few statements. 



" Dr Adler gives the facts upon the discovery ' of the Parthen- 

 ogenesis of Rhodites rosae' on ten pages, about two-thirds of the 

 first part of his memoir. 



''In May 1872, Rh. rosae in large numbers was gbserved ; 

 some few males appeared, which were put, together with several 

 females, in the breeding cabinet ; but no copulation was observed. 

 For further experiment were chosen females appearing later, of 

 which, by careful observation, it was certain that none of them 



