PARTHENOGENETIC DEVELOPMENT OF THE EGGS AND EGG FRACTIONS OF ARBACIA PUNCTULATA CAUSED BY MONOCHROMATIC ULTRAVIOLET RADIATION

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Abstract
1. Ultra-violet radiation either by the full arc for 1/10 to 10 seconds or by monochromatic radiation of 2260-2480A for two to eight minutes causes activation in normal unfertilized eggs of Arbacia punctulata, in the centrifuged whole eggs and in the halves and quarters derived from the whole eggs by centrifugal force. 2. Cleavages of the eggs and fractions have been obtained up to a 12- to 16-cell stage. 3. The nuclear phenomena of the nucleate eggs seem to be normal for the first cleavage, but in later cleavages many abnormal mitoses occur, chiefly multipolar and anastral. 4. Fractions of eggs without nuclei are activated by ultra-violet radiation just as they are by hypertonic sea water. These parthenogenetic merogones cleave and go to a 12-cell stage quite similar to that of a nucleate egg. 5. The ultra-violet radiation affects, therefore, primarily the cytoplasm.