SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 137 



RICHARDS AND PIPA, PL. 1 



I, Thick sheet of air-dried arthropodin with ridges and trapped air bubble, 

 viewed in polarized light between crossed Nicols. 2-4, Large artificially drawn 

 arthropodin fiber which tapers from about 50fi to iS/x at the tip. Crossed 

 Nicols: compensated to extinction (2), uncompensated (3), and compensated 

 to maximum brightness (4). Cross hairs partly visible as oblique lines. 5, Cross 

 section of normal cockroach tendon (100 x 150^1). Brightest along lumen. Crossed 

 Nicols, no compensation. 6, Another cross section at smaller part of tendon 

 (40 x 120JU,) showing clear lumen. Crossed Nicols, no compensation. 7, Por- 

 tion of another cross section showing great intensity parallel to surface of 

 elongated lumen. Crossed Nicols, no compensation. 8, Oblique and cross sec- 

 tions from the same field to show relative intensity of birefringence (intervening 

 area from this print cut out to save space). 



