A study of the effect of radium upon the eggs of Ascaris megalocephala univalens

Conclusions

My observations support the conclusions ofPerthes andHertwig that the achromatic figure appears perfectly normal; that the first segmentation divisions are regular; and that irregularities enter sooner or later which cause the death of the embryo. They further support the conclusions ofHertwig that the effect of the radium manifests itself in the first segmentation division and that the chromosomes are broken up into irregular masses and granules. In addition to these, I find that in the first segmentation division, the enlarged masses of chromatin which are similar to the cast off ends in the somatic cells of normal segmentation, may or may not take part in nuclear reconstruction and the succeeding division; that the chromatin of the first segmentation division is more greatly disturbed than in the divisions which follow. More important, however, than these is the fact that the chromatin of the sex and somatic cells in the second and third segmentation divisions behaves differently. That is, while the chromosomes of both cells break up, the fragments in the sex cells are generally larger.