Note 70 — PART II.
Reading edition
The lower door here, as in the branched nest (see above, p. 100), is sometimes united to the silk of the tube below by two nearly triangular gussets of silk, when, instead of being free except at the hinge, as I have represented it (Plate XII.), it is surrounded on either side by silk and only free at the extremity away from the hinge. This does not, however, alter the function of this door in any way.
It may be that these lower doors are always attached from below in this way, but it is very difficult to be sure of this, as they readily break away from the surrounding silk, when they appear quite free, as in my drawing. It was not until I adopted the plan of stuffing the tube full of cotton wool before removing the surrounding earth that I detected this fragile attachment.