380 WHEELER. 
DESCRIPTION OF PLATE XVIII. 
Doryphora decemlineata. 
Fic. 56. Portion of a longitudinal section through a young egg shortly after the 
germinal vesicle has reached the periphery. //, karyoplasm; ¢, protoplasmic trabe- 
culz connecting the karyoplasm with the intervitelline protoplasm (cytoplasm of the 
large cell which the egg represents); y, yolk bodies; ¢f, follicular epithelium; 74 
germinal spot (nucleolus); 74, maturation balls (Reifungsballen of Stuhlmann) Zeiss 
zz, oc. ITI. 
Fic. 57. Section corresponding to that of Fig. 56 from an egg almost mature. 
n, large mass of chromatin destined to enter into the first polar spindle; 4/, layer of 
surface protoplasm; y, yolk bodies; ef, follicular epithelium. Zeiss 7'z, oc. III. 
Fic. 58. Longitudinal section of a mature egg. , resting nucleus originating from 
the mass of nuclein 2 of Fig. 57; 4/, differentiated peripheral layer of protoplasm; 
yy yolk bodies; z, vitelline membrane; ch, chorion. Zeiss 7/5, oc. ILI. 
Fic. 59. Portion of median transverse section of a mature egg. 7, first polar spindle 
in metakinetic stage; remaining references the same as in Fig. 58. Zeiss 3/5, oc. III. 
Fic. 60. Same section as in Fig. 59 of an cgg about to be deposited, nucleus 
in last stages of anaphasis; the peripheral mass /! the first polar globule. Remaining 
references the same as in Fig. 58. Zeiss ;',, oc. III. 
Fic. 61. Half of the median transverse section of an egg containing several nuclei 
1, n3, none of which have as yet entered the surface layer of protoplasm é/. y, yolk. 
Fic. 62. Half of the median transverse section of an egg shortly before the blasto- 
derm stage. v, yolk-cells; a, blastema cell resting; 4, blastema cells in metakinesis; 
c, blastema cells in anaphasis; 4, yolk. 
Fic. 63. Half of the median transverse section of an egg in the blastoderm stage. 
v, yolk-cells; d/d, blastoderm. 
Fic. 64. Half of a median transverse section of the egg of Fig. 67. g, half of the 
gastrular groove forming on the ventral face; 7, ridge separating the groove-from the 
remainder of the blastoderm; J, flat blastoderm cells on the dorsal surface of the egg. 
Fic. 65. Median transverse section of an egg carrying the embryo represented in 
Fig. 71. The upper half of the section passes through #? of Fig. 71, the lower half a 
little in front of x. sv, serosa; am, amnion; ecd, ectoderm; msd, mesoderm; e77, 
cells still forming part of the induplicated ectoderm at f/. which give rise to the ento- 
derm; y, yolk. 
Fic. 66. Ventral view of egg shortly after formation of blastoderm; the two paren- 
thesis-shaped ridges inclose the portion which will sink in to form the gastrula. 
Fic. 67. Ventral view of egg with gastrula more advanced. a, oral spade-shaped 
broadening of the gastrula; 4, the point at which the groove turns abruptly inwards; 
sv, serosa. 
Fic. 68. Lateral view of same egg. c/, procephalic lobes; remaining references 
the same as in Fig. 67. 
Fic. 69. Caudal end of egg represented in Fig. 70. g, gastrula; a, caudal fold 
of the amnion; 5s”, serosa. 
Fic. 70. Ventral view of an egg with gastrula fully formed. a, oral widening of 
the gastrula; am, cephalic fold of amnion; 47, brain thickening. 
Fic. 71. Slipper-shaped embryo removed from egg and unrolled. 1 to f%, indica- 
tions of the 3 pairs of thoracic appendages; as, amnion and serosa; am, cephalic 
fold of amnion and serosa; @, oral and x, anal end of gastrula; 4, maxillary region. 
