138 BRITISH APHIDES. 



what information may be gained by the study of 

 embryonic and larval forms in Aphis ; to watch if any 

 ancient type really shows itself as recurrent in such ; 

 and to learn if any organs, traceable in the larvae, are 

 lost or atrophied in the adult ; such organs having been 

 beforehand persistent in a lower group. 



Von Siebold, in 1839, carefully investigated the 

 organs of reproduction of Aphis lonicerce, and he con- 

 firmed Dutrochet's discovery of the spermatheca and 

 the colleterial glands of the oviparous female. He 

 described three forms of Aphis lonicerce, viz. the winged 

 male, the winged viviparous female, and the apterous 

 oviparous female, which last insect he showed was the 

 produce of the winged female. 



The curious reproductive phenomena of these insects 

 led Steenstrup* and other authors to consider the 

 parents not as ordinary females but nurses (Ammen). 

 Some regarded the whole reproductive apparatus as a 

 collection of germinal stalks, and others looked on 

 them as fictitious or false eggs. The arguments for and 

 against have been considered by numerous investiga- 

 tors, and therefore it will not be well here to enter upon 

 the intricacies of so large a subject. On the other hand, 

 Siebold, Owen, Victor, Carus, and Burnett asserted 

 that there was a clear difference between the true ovum 

 and the yolk-mass which appears in the chambers of 

 the larval forms. These last bodies develop without 

 concurrence of any male element. Some denied that 

 they possessed a germinal vesicle. 



Leydig, Huxley, Brandt, and others state their con- 

 clusions that there is no histological difference between 

 the young organic germ and the true ovum. 



In 1858 Prof. Huxley discussed the development of 

 the false egg or " pseudovum," and then described, in 

 another genus of Aphis, the ovum or true egg, together 

 with its manner of development from the ovarian 

 chambers. Finally, he compared, in the same paper, 

 the organic and the sexual processes of generation. 



# Steenstrup, 'Alternation of Generations,' p. 108, &c., Ray Society. 



