DEVELOPMENT OF TIUCHOGRAMMA EVANESCENS. 187 
Fig. 28. — Section such as that through points X y X y in fig. 27. 
X is a cell whose nucleus has temporarily resumed the usual reticulate 
arrangement. Compare PI. 12, figs. 40-43. 
PLATE 12. 
Fig. 29. — Transverse section through brain and thickening 
which secretes the horn-like process. Same age as embryo in PI. 11, 
figs. 27 and 28. 
Fig. 30. — Horizontal section through head region of a young larva 
to show liorn-like processes (P. R. C.), mesenteron ( MES .), and mouth 
(M. T. H.). 
Fig. 31 — Transverse section through developing stomodseum. Same 
embryo as that in PI. 11, figs. 23, 24, and 25. 
Fig. 32. — Cast-out mass of cytoplasm with the extruded nuclei. Has 
become round, and the nuclei still live (Zb E. N.). 
Fig. 33. — Transverse section of larva near midgut when it begins to 
take in food ( F .). 
Fig. 34. — Longitudinal section through germ pocket ( G . C. P.) of 
same embryo as that in PI. 11, fig. 27. 
Fig. 35. — Part of embryo and the extruded mass ( E . HP.) with some 
nuclei still living ( L . E. N.). 
Fig. 36. — A germ cell of blastoderm stage containing the faint 
remains ( G .) of the germ cell determinant. 
Fig. 37. — Transverse section through germ cell pocket ( G.C.P .) in 
same embryo as that in Pi. 11, fig. 28. 
Fig. 38. — Larva in transverse section after it has began to swallow 
yolk ( F .), and when the body becomes stretched thereby. 
Fig. 39. — Transverse section through embryo after the stage drawn 
in PI. 11, fig. 24, to show formation of body cavity (C. A. V.). 
Fig. 40-43. — Stages in the resumption by mesoderm nuclei of the 
typical reticulate arrangement. Compare fig. 34 at X. 
