ClipArt ETC
"Longitudinal vertical section of frog embryo, shortly before closure of blastopore. FB., fore-brain; EC., ectoderm; N., notochord; SC., canal of spinal cord; NE., nerenteric canal; B., blastopore; M., mesoderm; P., beginning of pituitary invagination." -Thomson, 1916

Frog Embryo

"Longitudinal vertical section of frog embryo, shortly before closure of blastopore. FB., fore-brain;…

"Life history of a frog. Developing ova." -Thomson, 1916

Frog Stage 1

"Life history of a frog. Developing ova." -Thomson, 1916

"Life history of a frog. Newly hatched forms hanging to water-weeds. Stages with external gills." -Thomson, 1916

Frog Stage 2

"Life history of a frog. Newly hatched forms hanging to water-weeds. Stages with external gills." -Thomson,…

"Life history of a frog. Tadpoles during emergence of limbs." -Thomson, 1916

Frog Stage 3

"Life history of a frog. Tadpoles during emergence of limbs." -Thomson, 1916

"Life history of a frog. Tadpoles with both pairs of limbs apparent." -Thomson, 1916

Frog Stage 4

"Life history of a frog. Tadpoles with both pairs of limbs apparent." -Thomson, 1916

"Life history of a frog. Metamorphosis to frog." -Thomson, 1916

Frog Stage 5

"Life history of a frog. Metamorphosis to frog." -Thomson, 1916

"Dissection of tadpole. DL., Lower lip; H., ventricle of heart; DE., oesophagus; NA., head kidney; A., aorta; K., kidney; KU., ureter; DO., cloaca; LH., hind-limb; KV., opening of ureter into cloaca; GR., genital ridge; GF., fatty body; LF., fore-limb; OG., gills; a, epidermis; b, dermis." -Thomson, 1916

Tadpole Dissection

"Dissection of tadpole. DL., Lower lip; H., ventricle of heart; DE., oesophagus; NA., head kidney; A.,…