110 bulletin: museum of comparative zoology. 



spermatocytes during the "semiresting stage"; in one of these the 

 monosome Hes in the cytoplasm, while in the other it is located within 

 the nucleus. Similar conditions have been described by Baum- 

 gartner (:04) and Gutherz (:07) in Gryllus, and by Otte (:06) in 

 Locusta. 



During the second maturation division the monosome can always 

 be easily recognized by its relative size. Figure W (p. 106) shows 

 an equatorial plate of this division with, and Figure T one without, 

 the monosome. During the second division the monosome divides 

 longitudinally, one arm of the U going to each pole (Fig. 197), but it 

 always lags behind the autosomes. During the early telophase the 

 monosome can always be recognized projecting out from the mass of 

 chromosomes which are collected at each pole of the spindle (Fig. 

 199). Figure 198 shows the same stage where no monosome is present. 



In the spermatids the monosome retains its compact structure until 

 a much later stage than in the Acrididae, being recognizable up to a 

 late stage in the metamorphosis. However, it is, of course, present in 

 only one-half of the spermatids. 



5. The Metamorphosis of the Spermatids. 



A. Dissosteira Carolina. 



The metamorphosis of the spermatids appears to be practically the 

 same in all the Acrididae, so I have thought it necessary to describe 

 the process in only one species. During the telophase of the second 

 maturation diA-ision (Plate 5, Fig. 80) a nucleus is formed in each cell, 

 as usual. The autosomes rapidly disintegrate and become scattered 

 through the nucleus as fine granules suspended in linin meshwork 

 (Fig. 81). The monosome, however, does not break down until 

 later, but forms a conspicuous element in one-half of the spermatids, 

 where it appears as an elongated deeply staining body immediately 

 within the nuclear membrane (Fig. 81). For some time the spermatids 

 are connected by the interzonal filaments of the second maturation 

 diA-ision, which are at first very conspicuous but gradually disappear. 

 Meanwhile, a deeply staining mass has appeared by the side of the 

 nucleus at the end of the interzonal filaments. This body, which is 

 evidently the Nebenkern, is at first irregular in shape, very finely 

 granular, and stains deeply with Bordeaux. Apparently it is derived 

 chiefly from the mitochondrion (which it closely resembles), although 

 the interzonal filaments may also be concerned in its formation. 



