#ThrowbackThursday: Division Hypotheses Is Presented


By Science and Technology Staff

The entiretey of this article originally appeared in the Concordiensis on Nov. 11, 1960. The article’s original capitalization and grammar have been preserved.

Raymond Rapport, Jr., Associate Professor of Biology, lectured on division in animal cells last Wednesday to a joint meeting of Sigma Xi and the Pre-Medical Society.

He first proposed three basic hypotheses of cell division and then attempted to explain how his work is related to these theories.

The first conception was that a cell divides in a plane by the force executed by a deepening furrow.

The second hypothesis was that a constricting ring of protoplasm surrounds the cell and forces the division.

The final hypothesis was the expansion theory. When one cell splits into two, there is a 26 percent increase area.

According to the first hypothesis the surface is composed of the inner surface of the original cell, while the surface of the constricting ring cell is composed of the original surface if the cell which has thinned-out.

His first experiments were with a common marine organism. He studied how the cellular division of this animal was affected by the removal and the distrubance of various parts of the cell.

By marking various parts of the cell with carbon particles he was able to study the comparative movements of the cells’ constituents.

By attaching weights, which were very small glass beads, on-to sea urchin eggs he was able to observe the affect an extreme stress had on cell division.

This is done by placing the specimen on a glass plate, placing beads on top and then inverting the apparatus which would then support the cell with a weight applying stress on the opposite end of the organism.

In conclusion, Rappaport hinted that his work was inconsistent with the constricting ring theory. However, he doubted if this conclusion was the simple solution.


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