Memoirs: The Cyplasmic Inclusions of the Germ-Cells

Abstract

(1) The ovotestis of Helix aspersa is formed of fingerlike diverticula. The latter are hollow at their lower ends, which connect to the hermaphrodite duct, while the upper ends contain more yolk, and are filled completely with metamorphosing male cells. (2) According to the manner of derivation--that is, the nutrimental conditions of the locality from which new cells arise, and the number (if any) of times which these new cells divide--there are quite wide differences in the individual generations derived from and under such varying conditions. (3) These differences are found in nucleus, mitochondria, Nebenkern, and general cell volume. (4) The mitochondria vary in size and number, and such variation seems to be caused by the varying number of spermatogonial divisions in different regions of the ovotestis. (5) In the early spermatid smaller mitochondria, the micromitochondria appear in an unknown way near the region from which the axial filament takes its origin from the centro some applied to the nucleus. These micromitochondria are about one-fourth the size of the other, or macromitochondria. No perceptible variation in size of the micromitochondria of various generations has been found. (6) The micromitochondria form the front sheath of the sperm; the hind region of the micromitochondrial sheath intercommunicates with the macromitochondrial sheath, which follows behind. (7) The Nebenkern does not apparently become absorbed into the substance of the mitochondrial sheath. A sloughing off appears to take place. (8) The minute cytology of the derivation of the sperms, eggs, and nurse-cells is described. (9) The determination of the sex of the indifferent cell seems to be brought about by a variety of causes. The explanation of femaleness by presence of yolk cells is held to be inadequate, for male progerminative cells also appear in regions choked with yolk. (10) The probable function of the Nebenkern is discussed.