On the mechanism of prometaphase congression: chromosome velocity as a function of position on the spindle

Rates of movement of univalents at prometaphase and of half-bivalents at anaphase in living cricket and grasshopper spermatocytes were determined as a function of the distance from the pole toward which the movement was directed. In the artificially produced univalents of cricket cells, correlation coefficients for rate versus distance form the pole were widely disparate from movement to movement and there was no consistent relationship between velocity and distance from the pole. However, in the naturally occurring univalents of grasshopper cells, there was a significant positive correlation between velocity and distance from the pole. In both cricket and grasshopper cells, there was no consistent correlation between rate of movement and distance from the pole for half-bivalents at anaphase. The prometaphase data from grasshopper cells support the simple hypothesis of Ostergren (1950) that congression results from the application to chromosomes of forces which increase with increasing distance from the pole. Furthermore, these data are consistent with models of force production which suppose that the relationship between force (reflected as velocity) and distance from the pole is a linear one.