| Description | Slide shows four diagrammatic drawings of the 'Polarity and bilaterality in the frog's egg.'
None of the diagrams are named. However, the top left drawing has the words 'future front end' written above it, and 'future hind end' written below it. The image next to it has the same, plus the word 'belly' written on the left, and the word 'back' written on the right. The bottom right image has the word 'back' written above it, the word 'left' on the right side, the word 'belly' below it and word 'right' on the left side.
Title below images reads: 'Fig. 2 Polarity and bilaterality in the frog's egg. Above, in equatorial view ; below, seen from the vegetative pole; left, before fertilisation; right, after fertilisation. The unfertilised egg possesses a single main axis (polarity) at fertilisation, bilaterality is established through the formation of the grey cresecent in or close to the future mid-dorsal line. (From Wells, Huxley and Wells, The Science of Life, London, 1929.)' |