92 bulletin: museum of comparative zoology. 



distributed along the spireme thread, which at this time has a consid- 

 erable size. Throughout this stage the spireme retains its distinct 

 polarity, although, as in the Acrididae, the loops tend to assume a 

 peripheral position. 



2. Monosome. 



The monosome during the early part of the growth period (stage a) 

 is inclosed in a separate vesicle lying next the concave side of the 

 nucleus, but always separated from the nuclear wall by a thin layer of 

 cytoplasm (Plate 3, Figs. 53, 54). At this time the monosome usually 

 appears as a rounded, deeply staining, homogeneous mass, but on 

 strong decolorizing shows a distinct granular structure. The whole 

 appearance is strikingly like that of the same element in the resting 

 spermatogonium. Later the monosome becomes flattened, so that 

 it has the shape of a plano-convex lens, the flat side being applied to 

 the exterior of the nuclear membrane (Fig. 55). In the following 

 stage (d) the monosome (Fig. 56; Plate 7, Fig. 151) has become en- 

 closed within the nuclear membrane. It now forms a deeply staining, 

 somewhat elongated and flattened element closely applied to the nuclear 

 wall and connected at one end with the distal pole; but it soon becomes 

 converted into a U-shaped body by the development of a longitudinal 

 spht (Figs. 152, 153). In stage /the monosome (Fig. 154) forms an 

 irregular, vacuolated plate, the arms of the U having fused along their 

 entire length. 



In the spermatoc}i;es of Steiroxys the mitochondrion has a very 

 different form from that found in the Acrididae. Instead of being 

 distribvited irregularly through the cell, it is collected into a rounded 

 mass, which lies in the cytoplasm at the distal pole (Plate 3, Fig. 56). 

 This body, which is distinguished from the surrounding cytoplasm 

 by its deeper stain, is very finely granular and usually shows a still 

 more deeply staining layer around the periphery. Sometimes the 

 entire body is composed of several deeply staining rings separated by 

 lighter areas. A very similar condition of the mitochondrion has 

 been described by Otte (:06) in Locusta. In addition to the mito- 

 chondrion an interzonal body is present at the distal pole and appears 

 essentially the same as in Dissosteira. 



