Slide showing six diagrams illustrating the effects of cauterisation on a regulative insect egg Slide shows six black and white diagrams illustrating the effects of cauterisation on a regulative insect egg. Each diagram has a variety of labels, and the diagrams are labelled 'a' to 'f'. Title below image reads: 'Fig. 259. Effects of cauterisation on a regulative insect egg (see text). (a), (b) Increasing extent of cauterisation; (c) surface view of (b); (d), (e) only the extra-embryonic blastoderm develops; (f) normal development when cauterisation is late' A key then follows which reads: 'Key for Figs. 258 and 259. K, Blastoderm; At, antenna; Au, eye; D, yolk; EBl, extra-embryonic blastoderm; M, mandible; Md, midgut; Mx, maxilla; Th, thoracic leg; St. stomodaeum; A, cauterised portion; Wv, wound healed.' Late 19th to early 20th Century