The Cytoplasmic Inclusions of the Germ-Cells. PART III. The Spermatogenesis Of Some Other Pulmonates.1

Abstract

ABSTRACT Eight species of Pulmonates have been carefully studied, and certain stages of four more species examined. A new set of plasmatic bodies, the post-nuclear granules have been described. The P.N. granules differ from the mitochondria in their staining affinities, but resemble them in size. The P.N. granules ultimately form a plate at the rear of the spermatid nucleus. This plate, at first large, gradually shrinks synchronously with the shrinkage stages in the nucleus. The P.N. granules appeal’ to become non-staining during the maturation division, but it is not known whether more intense chromatization of the material (Benda) might not bring them into evidence. The mitochondria of the Pulmonates so far studied are of the same general type. On p. 239 twelve conclusions are given with regard to the mitochondria both of Pulmonates and of other forms. The chondrioplasts of all the Pulmonates dealt with have been fully examined. The chondrioplasts of different genera and often of different species tend to differ a little in shape aud size. The chondrioplasts during the prophases of the first maturation karyokinesis lose a great deal of their staining affinity. In many cases during the metaphase, anaphase, and telophase it cannot be demonstrated without specially heavy chromatization and staining. During these periods it changes, in its chemical constitution. The centrosome is responsible for the sorting out of the chondrioplasts into two equal groups at the prophase of division. The batonette is not divided by fission, but goes to the daughter-cell complete. After the final maturation division is over, the chondrioplast rod resumes its lost staining affinity. The chondrioplast batonettes do not take direct part in the formation of the spindle. The micromitochondria have been thoroughly re-examined with iron hæmatoxylin and Benda’s method. Their presence is confirmed by all tests that could be made. They seem to differ in staining capacity from the macromitochondria. The presence of micromitochondria in other forms is doubtful, because the cells are so small as to make proper examination impossible. Micromitochondria appear to be present in Limax agrestis and in H. rufescens. The mitochondria, during the maturation divisions, stain less heavily, and often become larger. The latter fact could not be demonstrated in every case. On p. 248 I have stated the periods during which the mitochondria, appear to alter in staining affinity and resistance to certain fixatives. The affinities of the several species have been discussed on the basis of their cytoplasmic bodies. Tables of staining and fixing effects have been given. From the three papers already published on the “Cytoplasmic Inclusions “it will be seen that strong evidence is being collected against the view that the mitochondria take any part in the transmission of the “factors of heredity.”