Plate XII.
Quite a gigantic specimen of the chief spiral – the "Haupt-Spiral" of Curschmann. The many kinks and turns and windings of the tube, and the much-crossed and interlaced fibrils and spindle cells of which its walls are composed, come out pretty well. In this example the central thread is certainly nothing more than the lumen of the spiral, whose walls are too tough and elastic to admit of their collapse, either empty space or filled with air. The circular dark spot at right hand lower corner has been caused by a microscopic fault in the gelatino-bromide dry plate.
Objective, Carey's 1/4
Magnification, 150/1
