124 



tung seino Flugel entwickele". As he himself cites Swam- 

 merdam's discovery of the subimago of the Ephemeridae^ it must 

 also be known to him that Swammerdam described (Biblia Naturae 

 I, p. 269 and Historia Generalis p. 87): "how in June 1670 in the 

 neighbourhood of the village of Slooten, the subimagines flew upon 

 his coat, that they moulted there and returned directly afterwards 

 to the water." By this observation the argument of Boas is refuted, 

 ilk my opinion, more than two hundred years before it was used. 



De Lameere (1900) tries to find the origin of holometabolism 

 in the habit, insects acquired by penetrating into vegetable tis- 

 sues. The different Holometabola might therefore be derived mono- 

 phyletically from the Neuroptera. Handlirsch raises many im- 

 portant objections to these conceptions (See p. 126). 



P^Riiz (1903) mentions several causes, but, as Henneguy 

 (1904, p. 692) rightly observes, these are not explanations, but 

 only statements of facts. 



Heymons (1907) lays emphasis upon the great changes, which 

 the so-called Ametabola undergo (e. g. Machilis). He says on 

 p. 160, that the pupa is a new stage. Naturally we must not 

 think that no trace of it is to be found in the lower insects : 

 „E8 kann erstens die Holometabolenpuppe das umgewandelte 

 letzte Larvenstadium oder die 8umme der letzten Larvenstadien 

 der Hemimetabolen repriisentieren, oder es kann zweitens die 

 Puppe weiter nichts als eine unvolkommene Imago selbst, ge- 

 wissermassen eine vorlaufige noch unfertige Ausgabe der Imago 

 sein." Heymons adopts the latter alternative and is therefore an 

 adherent of the subimaginal theory. He thinks besides that the 

 Lepidopterous pupa has become secondarily movable again. In 

 this connection I think attention should be drawn to the investiga- 

 tions of Chapman (1893) who demonstrated that it is exactly 

 the pupa incompleta which occurs in the lower families. He also 

 directed attention to the fact that the pupae are generally much 

 more movable than is usually supposed. In my opinion the mova- 

 bility of the Lepidopterous pupa is to be considered a primitive 

 characteristic. 



