No: 2.] BLATTA AND DORYPHORA. 207 
disappears in all but a few of the recorded cases both in plants 
and animals. Moreover, the two daughter nuclei are frequently 
very unequal in size. 
The chorion (Fig. 1) is a thin, chitinous membrane smoothly 
covering the surface of the egg. In surface view it appears to 
be finely granular, the finest granules being arranged in large, 
more or less regularly hexagonal areas, which are bounded by 
narrow, dark spaces containing somewhat larger though less 
dense granules. Each of the hexagonal areas is secreted by 
one of the polygonal epithelial cells described above. It is only 
in cross-section that the true structure of the chorion becomes 
apparent. According to Blochmann (5),—and my observations 
coincide with his, —the chorion consists of two chitinous laminz 
kept in close apposition by means of numerous minute trabe- 
culz, or pillars. It is the ends of these pillars seen in surface 
view that look like granules. In the spaces between the hex- 
agonal areas, the trabecule are more scattered and individually 
thicker than those of the hexagons. Hence these lines on the 
chorion seem covered with larger and more scattered granules. 
When pieces of the dry chorion are immersed in glycerine and 
immediately examined under the microscope, the thick liquid 
may be seen entering the spaces between the hexagonal areas, 
passing along them in obedience to the laws of capillarity, and 
then slowly creeping from them on both sides into the adjacent 
hexagonal areas between their denser trabeculz. I have also 
observed that the structure of the chorion of the ripe egg is 
most distinct in cross-section at the pole directed towards the 
germarium. Here the two lamine seen at vo in Fig. 4 separate 
somewhat, and the connecting trabeculae become longer and 
more distinct. 
I have not been able to trace the formation of the micropyles 
in Blatta germanica. Their structure is easily demonstrated. 
They are scattered over a quadrant of the upper hemisphere 
where the beautiful hexagonal pattern of the chorion gives 
away to an even trabeculation (Fig. 2). The micropyles are 
wide-mouthed, very oblique, funnel-shaped canals perforating 
the chorion (Fig. 2 «2, 0). ) Uhe apertures of the funnels 
appear under a low power as clear, oval spots, the long axes of 
which are parallel to the long axis of the egg. These perfora- 
tions are scattered over the micropylar area, sometimes in clus- 
