6 HAROLD H. PLOUGH. 



and the second from a living cell stained with janus green. The 

 first shows the diplotene threads clearly polarized toward the 

 idiozome, while the second the indefinite heavy threads polarized 

 toward a vacant space in the cytoplasm outlined by the mito- 

 chondria. After the diplotene stage the idiozome is never visible. 



The failure of previous observers to identify an attraction 

 sphere in at least some of the Acrididae is rather peculiar, for it 

 seems almost certain that it has been figured before. A body of 

 similar appearance, called by Davis a "mitochondrion," is shown 

 in at least his Figs. 31, 34 and 42. In view of the observed 

 behavior of the mitochondria this is of course incorrect, and it 

 seems improbable that it can be a mitosome at the stages indi- 

 cated. As has been observed above, however, the idiozome is 

 not always visible, and when taken in conjunction with the 

 fact that a clear polarization of the threads is sometimes hard to 

 find, this may indicate that the idiozome is a structure which is 

 sometimes present and sometimes not. 



It remains to trace the behavior of the "neutral red granules" 

 during these earlier stages of the growth period. As stated above 

 and shown in Figs. 2, 3 and 4, these granules are larger than the 

 mitochondria, stain densely with haematoxylin, and may lie 

 anywhere in the greatest mass of cytoplasm. When the diplo- 

 tene stage is reached (cf. Fig. 5) we find instead of several granules 

 a single rather large spherical mass lying in a clear vacuole. 

 It is now exactly similar, though smaller, to the chromatoid body 

 of Pentatoma seilis described by Wilson. This body stains very 

 heavily with haematoxylin, while in the living cell it is practically 

 invisible. When the living material has been treated with neutral 

 red for about an hour, however, it appears as a highly refractive 

 pink drop in the cytoplasm (Fig. 8). Intermediate stages be- 

 tween these two conditions have not been found in the living 

 material, and even in the fixed preparations one usually finds 

 that the cells from the massive body stage on, contain a single 

 chromatoid body in the cytoplasm. Cells are found now and 

 then in which several granules are apparently fused in one mass, 

 or in which two seem in the process of fusion, as in Fig. 3. It is 

 certain at least that the single chromatoid body appears at the 

 expense of the earlier small granules, and this fact makes it 



