385 



Deegknku (1009) supposes the rigidity of tlio clutiiioiis 

 skin to 1)0 the eausc of the iiioultiiigs and lic tliiiiks (p. 19 

 sqq.) : ''that tlic liig-hor spccialized insects possess a tondeiicy and 

 a will to diminish the nuniber of these moultings. This can only 

 be achieved by retarding the development between two moul- 

 tings, and so attaining by one ecdysis what otherwise could only 

 be attained by many. The more these moultings were reduced 

 in number, the less recapitulations of phylogenetic stages had to 

 be passed by the larva, and so it makes the impression that 

 phylogenetically its development is retarded, and ontogenetically 

 it remains all the longer in a primitiye state, by retardation of its 

 development. Througli this, the larva has the opportunity of 

 specializing itself, according its own desire and character. The 

 great difference has arisen in consequence of a different manner 

 of life, especially the aquatic one. Pupa and subimago are 

 not identical, but they are both primary stages of development, 

 which have remained preserved." 



Bastin (1913) and Carpenter (1913) arè both adherents of 

 the subimaginal theory, especially the latter, who has published 

 a short but very interesting treatise, which contains a great many 

 facts and is written witli great conviction. 



In constructing a theory on the origin of the pupal state it is neces- 

 sary to study the subject from as many different points of view as 

 possible. By Weismann's investigations especially (1863, '64, '66), 

 later on continued by i.a. J. van üees (1888), Mesnil and Metsch- 

 NiKOFF (1900), Bauer (1904), Janet (1909) and Poyarkoff (1910), 

 tlie attention of the investigators has been turned more to the 

 histological processes and in the first place to the histolysis in tlie 

 pupal stage, tlian to the purely morphological problems. Histolysis 

 may be considered to be a secondary phenomenon, but from that 

 it does not follow that the pupa itself is secondary. The larva of a 

 frog is not secondary because its tail disappears by phagocytosis ! 

 It is therefore desirable to direct the attention to palaeontology, 

 whicli has been greatly neglected by many entomologists. On this 

 point 1 refer especially to the last of the three following writi^rs: 



