DAVIS: SPERMATOGENESIS. 89 



E. INIelanoplus femoratus. 



1. Autosomes. 



During the growth period the same stages can be recognized as in 

 Dissosteira. In stage b (Plate 3, Fig. 45) the chromatin is aggregated 

 into well defined masses, as in Chortophaga, and the spireme threads 

 are later formed from these masses in a similar manner. 



2. Monosome. 



The changes which take place in the monosome during this period 

 are very different from an\'thing occurring in the preceding species, 

 but somewhat similar structures are found in Stenobothrus. However, 

 on account of the small size of the monosome in Melanoplus, it has 

 been impossible to trace its development as completely as in that species 

 During the early growth period the monosome forms a deeply staining, 

 somewhat flattened element apposed to the nuclear membrane. In 

 stage d it usually shows a distinctly bipartite structure (Plate 7, Figs. 

 115, 116), one component being slightly larger than the other. At this 

 time the two components are usually close together, but occasionally 

 they may be some distance apart. Later (stage e) the monosome 

 becomes distinctly vacuolated and one of the components begins to 

 lengthen (Figs. 117, 118); it continues to do so until, in the following 

 stage (/), it forms a much elongated granular body, which closely 

 resembles one of the spireme threads, and is on that account often 

 difficult to distinguish. The other component retains its compact 

 form. 



The mitochondrion is relatively more abundant than in Dissosteira 

 and is scattered irregularly through the cytoplasm forming small, 

 finely granular, flocculent masses, which stain deeply with Bordeaux. 



F. Stenobothrus curtipennis. 



1. Autosomes. 



The growth period in this species is, in general, much as in Dissos- 

 teira, although, on account of the relatively much greater amount of 

 chromatin, the material is, in many respects, less favorable for study. 

 Figure 47 (Plate 3) shows the first stage (a) of the spermatocytes. 

 Figure 48 shows the split spireme stage (e). Owing to the large size 

 of the loops, the polarity is never as marked as in the preceding spe- 



