854 THE AMERICAN NATURALIST. [VoL. XXXIII 
their growth. Their commoner forms are shown in the figures 
presented herewith. 
The basement membrane consists, we believe, of the fused 
inner ends of the hypodermal cells or of processes from them. 
It is often incomplete or fenestrated, and it is of extreme 
tenuity. Semper thought it (in the Lepidoptera) composed of 
leucocytes applied to the free inner ends of the hypodermal 
= 
——— aE al Ee Ee Tos 
= ae peat LO oS 
Fic. 87. — Sections of wings of Hippodamia 13-punctata, all drawn to on same scale: A, from 
full-grown quiescent larva, a bit of the wing crumpled under the loose larval cuticle; s, a 
5 
C, fore wing of a newly transformed imago; ž, pits above the chitinous pillars; D, hind 
wing of a newly transfor aa imago, showing especially the manner of formation of a 
special chitinous brace. 
cells, and his opinion has been concurred in by several subse- 
quent investigators ; but we are inclined to believe that in the 
forms we have studied, the formation of it from leucocytes is at 
least exceptional, for the following considerations :— 
1. While leucocytes are not infrequently seen lying against 
it, we have seen no direct evidence of their participation in its 
development. 
2. During early stages it is well formed and destitute of nuclei. 
3. In later stages, when, after the expansion of the wing, 
it contains distinct nuclei, there is evidence that some of these 
at least are derived from the hypoderm cells whose nuclei, once: 
crowded up to this level, have remained stranded there after the 
expansion of the wing. 3 
