DAVIS: SPERMATOGENESIS. 85 
102) forms an irregular flattened plate closely apposed to the nuclear 
membrane. It is usually somewhat vacuolated and tapers at one end, 
which is attached to the nucleus at the same point as the autosomes. 
The monosome usually lies near the distal pole of the nucleus rarely 
being distant more than 90° from it. During the following stage (e) 
there is very little change (Fig. 34), but during stage f the monosome 
undergoes a very interesting metamorphosis. At the beginning of 
this stage the monosome forms an irregular flattened plate closely 
applied to the nuclear membrane, and connected at one end with the 
distal pole of the nucleus. A view of the monosome en face (Plate 7, 
Figs. 103, 104) shows that it does not stain uniformly, but contains 
several lighter areas, where it is probably thinner than elsewhere. 
When strongly decolorized it can be seen to be composed of minute 
deeply staining granules imbedded in a less deeply staining matrix. 
At a little later stage (Figs. 105-107) the thin areas have become 
broken through so that the monosome becomes converted into a loop 
both ends of which are attached to the nuclear membrane at the distal 
pole. At this time the monosome has a very ragged outline and stains 
but little deeper than the other nuclear elements, so that it is often 
difficult to distinguish it. 
During the entire growth period the mitochondrion can be distin- 
guished as irregular masses scattered through the cytoplasm and stain- 
ing with Bordeaux more deeply than the latter. Usually, it is especially 
abundant at the distal pole of the cell, but also forms an irregular 
layer around the nucleus. At first the amount of mitochondrion is 
small, but it increases rapidly during the growth period and becomes 
a conspicuous element of the cytoplasm. In material fixed with 
Flemming’s fluid the mitochondrion is much more conspicuous and 
stains much more deeply than in Hermann material. In Flemming 
material it is usually distinctly granular and in some cases fibrillar. 
The interzonal body, which lies at the distal pole, so closely re- 
sembles the mitochondrion that it is often impossible to distinguish 
one from the other. In most cases the interzonal body.can be identi- 
fied with certainty only where it can be traced into an adjoining cell. 
B. Arphia tenebrosa. 
1. Monosome. 
The spermatocytes in this species are very similar to those in Dissos- 
teira, but are in some respects even more favorable for study. Plate 
