ANNALS 
OF 
The Entomological Society of America 
Volume VIII SEP TEMBER, (9.15 Number 3 
THE FORMATION OF THE MIDDLE MEMBRANE IN 
THE WINGS OF PLATYPHYLAX DESIGNATUS WALK. 
WILLIAM S. MARSHALL, 
University of Wisconsin. 
There appears to be some difference of opinion regarding 
the terms middle membrane and ‘‘Grundmembran,”’ their first 
formation and ultimate fate, and, at what stages in the develop- 
ment of the insect’s wing they occur. Semper (10), from whose 
paper the word ‘‘Grundmembran’’ comes chose for his work 
the later stages of some Lepidoptera and found, between the 
two hypodermal layers of the developing wing, a membrane-like 
structure which he called the ‘Grundmembran’’—this name 
has been adopted by others. Semper’s view as to the origin of 
this membrane from “ Bildungszellen’’ has been followed by 
some; we believe, however, the more widely accepted view to 
be that of Schaffer (9) who, speaking of the development of the 
wing in the Lepidoptera says: ‘‘Sehr fruh, etwas sobald die 
Schuppen sich anlegen, beginnt in ganz eigenartiger Weise die 
Verschmelzung der Flugelblatter.’’ Again: ‘‘Est is eine von 
Plasmen gebildtee continuirliche Membran vorhanden die ich 
als ‘Grundmembran’ des Epithels bezeichnen will.’’ Later the 
same worker says: ‘‘die Grundmembranen bei der Fligelblatter 
sich bereits dicht auf einander verschmolzen sind. Der Fltgel 
erscheint so aus zwei Epithelien zusammensesetzt, von denen 
gegen eine in der Mitte gelengene Membran pfeilartige Fortsatze 
auslaufen.”’ 
What one might call the generally accepted view regarding 
the middle membrane is this: The basement membrane covering 
the hypodermis of the young developing wing is similar to that 
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