No. 3-] THE EMBRYOLOGY OF A TERMITE. 513 



This is brought out better in the following stage, which exhibits 

 two cells in the enlarged end, one on the shorter axis, and one 

 in the small end ; that is, there are three nuclei nearer the 

 posterior than the anterior pole (PI. XXIX, Fig. 4). The cleav- 

 age becomes irregular with the eight-cell stage, one or more 

 nuclei dividing before the time for a typical rhythm of divisions. 

 For several divisions there is a slight preponderance of cells in 

 the larger end of the egg. For instance, one ^g^ has four 

 nuclei in this end, one on the shorter axis, and three anteriorly ; 

 while another has five in the posterior, and four in the other end 

 (PI. XXIX, Fig. 5). Generally, during the early stages of 

 cleavage, there are three or four more cells in the larger than 

 in the smaller end of the egg. After five or six divisions, the 

 resulting nuclei have taken positions at about equal distances 

 apart through the yolk. The nuclei are each surrounded by a 

 little mass of protoplasm, and may consequently be spoken of 

 as cells. As far as can be determined, there is no proto- 

 plasmic continuity between these cells at this early period. 

 Later, when the embryonic disc begins to appear, continuity 

 is established between its cells ; but even then a connection 

 between the blastoderm cells of other regions, or between these 

 and the yolk-cells, is not made out with any degree of cer- 

 tainty. A view of the ventral surface of an q^^ at this stage 

 shows very well the equal distribution of the nuclei on that 

 side, and the same is found to be true of the nuclei on the 

 remaining surface of this Q.g% (PI. XXIX, Fig. 6). {Refer to 

 end of paper, to the explanation of Figs. ^ ajid ^, in regard to 

 cleavage) 



Most of the cells have now reached the surface, there being- 

 only a few in the yolk which lie at equal distances apart. In 

 properly prepared material, the changes that follow and lead to 

 the appearance of the embryonic disc can be most distinctly 

 traced in entire, transparent eggs studied in clove oil, cedar oil, 

 and balsam. The following description refers chiefly to speci- 

 mens studied in this way and to sections through certain stages. 

 I have already stated that the various stages are mixed together 

 indiscriminately when collected. The series illustrating the 

 growth of the disc had to be picked out from a great mass of 



