In figure 80, plate III, a pair of spermatids is shown with nuclear membrane formed and the spindle fibers twisted in a characteristic manner. Figure 81 is a slightly later stage with the spindle-remains massed against the nuclear membrane. Curiously enough there appears in the nucleus of every spermatid a body similar to the element _x_ of the spermatocytes of the first order (figs. 82-86). This body is often applied to the nuclear membrane and connected with the spireme (figs. 84-86). It decreases in size and finally disappears (figs. 88-91). The spindle-remains divides (fig. 83), and a small part of it (_a_) goes to form the acrosome at the apex of the head (figs. 85-92). The larger part is probably utilized in the formation of the tail, for it gradually disappears as the tail develops. The centrosome which, although small, is conspicuous in each mitosis, is seen in figure 83 between the two parts of the spindle-remains, applied to the outside of the nuclear membrane. In figures 85, 86, and 87 the relation of the tail (or its axial fiber) to the centrosome is shown. In figures 87 and 88, instead of the small spherical centrosome of figures 83 to 86, we have a much elongated body, at first (fig. 87) applied for its whole length to the nuclear membrane, but later lying along one side of a middle piece (_m_), as shown in figure 89, and in a later stage in figures 90 to 92. The mature spermatozoon with its forked anterior end appears in figure 93. The points of especial interest in the spermatogenesis of _Stenopelmatus_ are the development of the aberrant chromatin element _x_ during the growth stage of the spermatocyte of the first order, its distribution to one-half of the spermatocytes of the first order, its disappearance during the rest stage between the two maturation divisions, and the development of a similar, though smaller, element in all of the spermatocytes. Blattella germanica.