Table 2. Behaviour of the clones in respect to the rhombomeric boundaries.

	Theoretical	Observed	Expected	χ2 Discrepancy
Boundary-respecting	0.22	34	25.5	2.8
Boundary-crossing	0.57	12	66.1	44.3
Middle-clones	0.21	70	24.4	85.5
Total		116	116	132.6

Theoretical probabilities of crossing, respecting and failing to meet the rhombomeric boundaries by chance were computed from the sizes of clones relative to the AP length of the rhombomere, accounting for the measure error, as in ^[8]. We checked whether observed data do fit this theoretical probabilities using a classical χ² goodness-of-fit test. Results showed that we can reject the null hypothesis that observed data could come from the theoretical model (p<10⁻²⁸, df = 2).