116 Wisconsin Academy of Sciences, Arts, and Letters. 
in its middle showing the exact location of the dividing lines. 
In a microscopic preparation the character of the nuclei may be 
seen to change abruptly at this constriction. The anterior, 
conducting portion lies in the head and at the base of the labium 
joins with its fellow in a common duct rather strongly chitinized 
and leading to an opening at the tip of the labium. In this 
chitinized portion is the ‘ ‘ press ’ ’ which has been fully described 
by Gilson. (2, 3.) 
The secreting portion is made up throughout its length of 
cells containing the characteristic branched nuclei of spinning 
glands of insects but in the small cells near the anterior end 
the branching is not extensive. (Fig. 14.) Each cell, in sur¬ 
face view is typically the shape of a flattened hexagon, the 
shorter axes lying in the direction of the length of the gland, 
two such cells forming the entire circumference. Such a gland 
when opened along one side and spread out gives the appearance 
seen in the diagram. (Fig. 13.) The nuclei do not show dis¬ 
tinct centers of branching, as figured by Ilenneguy (6), nor 
are they broken up into separate fragments, as described and 
figured by Gilson. (3) They do, how r ever, in some cases of 
complex branching have this appearance, but a careful examin¬ 
ation with a high power shows a connection, in every case, of 
such apparently detached pieces with the main body of the 
nucleus. Whether or not the branches ever anastomose is dif¬ 
ficult to determine. Such anastomoses are shown by Helm (4) 
.for the nuclei of Lepidopteran glands, but such cases are rare, 
if they ever exist, in the corresponding structures of P. desig¬ 
nators. What at first appear to be such anastomoses are com¬ 
mon in the larger and more complex nuclei, but careful focus¬ 
sing and study of the outlines of the nuclear membrane, in a 
majority of cases, proves beyond a doubt that it is only appar¬ 
ent and not real, the appearance being caused by overlapping 
branches lying at different levels. (Figs. 15-20.) 
Nervous Svstem.— The nervous system shows a small 
degree of concentration in the larval stage. It consists of a 
chain of thirteen double ganglia, (Fig. 9.) which Betten (1.) 
says is the number given by Klapalek* for Trichoptera, though 
*Klapalek’s work was not available. 
