Driesch found that the one-half and one-fourth blastomeres develop into proportionate gastrulæ and larvæ; that the one-eighth blastomeres, both of the animal and the vegetative hemispheres, sometimes produce gastrulæ, and even the beginning of the larval stage with the rudiments of a skeleton. There are certain differences between the one-eighth larvæ that come from the animal hemisphere and those from the vegetative half. More of the one-eighth blastomeres from the animal part of the egg die than from the opposite part, but of those that remain alive a larger percentage reach the gastrula stage than in the case of those from the vegetative pole; their protoplasm moreover is not so clear as is that of the larvæ from the other hemisphere. These “animal pole” blastomeres develop faster than those of the other sort. The gastrulæ from the one-eighth blastomeres of the vegetative hemisphere do not die so often after separation, the protoplasm of the larvæ is clearer, and they often produce long-lived blastulæ with long cilia. The blastulæ often develop into gastrulæ without mesenchyme. These results show that although whole larvæ may be produced from the one-eighth blastomeres of both hemispheres, yet there are certain characteristics that may be referred with great probability to differences that are present in the protoplasm of the two hemispheres of the egg. The differences are not in all cases sufficient to interfere with the production of all the characteristic structures of the embryo, yet traces of the origin of the larvæ can be found in their structure. It is probable that the so-called animal (or micromere) pole corresponds to that part of the egg from which the archenteron is produced. Hence the one-eighth blastulæ from this hemisphere gastrulate sooner and in proportionately larger numbers than do those from the opposite hemisphere. The vegetative hemisphere would correspond to that part of the egg from which the wall of the normal gastrula is derived, and this may account for the clearer protoplasm of these embryos, their inability in many cases to gastrulate, their larger cilia, and the absence of mesenchyme in some of them. Driesch finds that the number of cells that go into the mesenchyme of the partial larvæ is in proportion to the total number, and that the number of cells in the archenteron is probably also proportionate.[118] The smallest blastomeres that produce gastrula are the one-sixteenth products. Out of a total of 139 cases only 31 produced true gastrulæ, 5 produced gastrulæ with evaginated archenteron, and 103 remained blastulæ with long cilia. The one-thirty-second blastomeres were not observed to gastrulate.