The part of the work of Driesch and Morgan, that has a special bearing on the _interpretation_ of the one-half and one-fourth development of the isolated blastomeres, is that in which some experiments are described which consisted in cutting off portions of the unsegmented egg. If a fertilized but unsegmented egg is cut in two by means of a small pair of scissors, the part that contains the nucleus may segment, and give rise to an embryo. The division is generally like that of a part, and in such cases an incomplete embryo develops. The embryo may have fewer rows of swim-plates than has the normal embryo, and fewer endodermal sacs, and the stomach may be in an eccentric position. The embryos resemble in every respect the incomplete embryos from isolated blastomeres. It is important to note that although the embryos from isolated blastomeres resemble those from pieces of the segmented egg, in the former case the nucleus has divided once, and each blastomere contains half of the original nucleus, while in the latter case the entire segmentation nucleus is present in the piece. These facts seem to show that in this egg the incomplete development is directly connected with the protoplasm, and not with the nucleus,--a view that is maintained by Driesch and Morgan in connection with these experiments. It was found in one or two instances that the nucleated pieces divided in the same way that the whole egg did, except that the blastomeres are proportionately smaller. From pieces of this kind whole embryos of small size developed. In this case we must suppose that the protoplasm has succeeded in rearranging itself into a new whole of smaller proportions.[123] Crampton (’96) has shown in a mollusk, _Ilyanassa obsoleta_, that when a blastomere is separated from the rest, the cleavage proceeds as though the blastomere or its products were still present, and the larva is defective in those organs that are normally derived from that blastomere. These results are in line with those on the ctenophore egg. Fischel (1900) has also made some experiments on the segmented egg of the ctenophore, and has confirmed several of the results obtained by Driesch and Morgan. In addition he has tried the effect of disturbing the first-formed cells by pushing them over each other, so that their relative positions are changed. He finds as a result that the paddles, sense organ, etc., appear in unusual positions, and the latter may be doubled. This shows that we must regard the material or structural basis of the organs as present very early in the different parts of the egg, and that the organs develop without much regard to their relation to other organs.