No. 3-] THE EMBRYOLOGY OF A TERMITE. 511 



ing imbedding often cause numbers of the yolk-bodies to fuse 

 together into large bodies. This may be very marked, large 

 spaces being left in the yolk by the solution of the oily fluids. 

 In sections single yolk-bodies are frequently found riddled with 

 holes, left by the solution of the oil drops formerly imbedded 

 in their substance (PI. XXXI, Figs. 30, 31, 34, 37, p. yb). 



I should derive the yolk-bodies in which oil drops have col- 

 lected from the homogeneous vesicles. The homogeneous 

 (albuminous) coagulable fluid of these bodies apparently be- 

 comes transformed into soluble substances which, first forming 

 in isolated drops, finally fill the whole vesicle. In this way the 

 oil globules and free oily fluids of the yolk would appear to 

 arise from the (albuminous .'' ) yolk-bodies, to furnish the growing 

 embryo easily assimilable nutriment. The sections (PI. XXXI, 

 Figs. 30, 33, and 34) show finely fragmented yolk-bodies lying 

 beneath the embryonic disc. Other sections do not show a 

 similar fragmentation, the solution having been more complete. 

 When yolk-bodies in which drops have collected are prepared 

 for sectioning by the usual methods, chemical changes take 

 place which result in homogeneous fused masses of stainable 

 (albuminous .-* ) substance, and in the solution and removal of the 

 fatty matters. 



There is apparently no definite arrangement of the different 

 yolk elements. There is no peripheral layer of protoplasm 

 distinguishable before the formation of a blastoderm. I have 

 found no " segmentation of the yolk " during the early stages 

 of development. 



Segmentation and the Changes in the Blastoderm 



Leading to the Establishment of the First 



Rudiment of the Embryo. 



The first sharply marked rudiment of the embryo is, as in 

 the case of certain of the Orthoptera (Stenobothrus, Stagmo- 

 mantis, Gryllus, and Oecanthus), a relatively small disc of 

 closely crowded cells at one pole of the ^^'g. Since the 

 history of the origin of these embryonic discs has not been 

 worked out, I have studied, with special care, the segmentation 



