No. 3-] THE EMBRYOLOGY OF A TERMITE. 529 



and drawn in PL XXXI, Fig. 28. It is flattened out with the 

 under (or yolk) surface uppermost. 



This embryo exhibits a uniform ectoderm, with cells some- 

 what more closely crowded in the cephalic lobes. Along the 

 borders of these expansions this crowding is greatest. At the 

 extreme front end of the band, in the median line, wedged in 

 between the lateral lobes, there is a small triangular area of 

 ectoderm, in some preparations much more distinctly shown. 

 Cells of the amnion are seen at the edges of the germ-band. 

 The under, mesodermal layer is shown in such preparations very 

 beautifully. Its cells being differently shaped from those of 

 the ectoderm, lying more loosely, and at the same time staining 

 rather more intensely, the entire layer stands out with remark- 

 able distinctness. A larger collection under the posterior end 

 of the band is apparent, as was shown in sections of the younger 

 embryo (PL XXXI, Fig. 37). Passing anteriorly the cells be- 

 come more scattered. Only two or three cells have wandered 

 forward into the cephalic lobes — the anterior end of the meso- 

 derm being fixed at the base of this region. Here there is a 

 little collection, on either side, under the posterior ends of the 

 cephalic lobes. 



Graber's (9) preparations of the germ-bands of Stenobothrns 

 variabilis, removed from the yolk in like manner, make a simi- 

 lar picture. His Fig. ']6 of Taf. VI represents a stage which 

 may be compared with my PL XXXI, Fig. 2"^, for the 

 Termite, though the cephalic lobes are not so broad in Steno- 

 bothrns. In the Termite the mesoderm does not lie so evi- 

 dently along the middle line, but forms a flat layer extending 

 nearly to the edges of the band. The earlier germ-bands of 

 the Termite have a shape somewhat different from those of 

 Stenobothrus (Graber (9), Figs. 74 and 75), and here again the 

 mesoderm is not so markedly on the middle line. 



General Sketch of the Development from the First 

 Appearance of Segments up to Hatching. 



Before proceeding to a discussion of the phenomena which 

 have been described, I shall trace the remaining course of 



