| Description | Slide shows three diagrams regarding 'the equality of nuclear division during cleavage' in terms of Triton Taeniatus (newt).
Diagrams are labelled A to C.
The explanatory text under the diagrams reads: 'The equality of nuclear division during cleavage. A fertilised egg of Triton taeniatus was constricted by a ligature, restricting the nucleus to the right-hand half, in which cleavage has reached the 8-cell stage, while the left-hand half is still undivided. A, At the 16-cell stage one of the cleavage-planes coincides with that of the ligature, and 1/16 nucleus has passed across into the as yet undivided left half. B, The ligature was then drawn tight so as to effect complete separation between the two (lateral) halves. C, Each developed into a perfect embryo (one slightly further advanced than the other); 140 days after the operation, they were identical. A nucleus of the 1/16 stage is therefore equivalent to that of the whole egg. (From Spemann, Zeitschr. Wiss. Zool. CXXXII, 1928).'
The slide is labelled 'Fig. 37'. |