158 RAYMOND BINFORD 
safranin it takes a dull red color. In the early stages of develop- 
ment the content of the capsule is stained green when the prep- 
aration is treated with the safranin and Lichtgriin combination, 
but in the later stages the green is masked by the red. In stages 
represented in figures 53 to 55 a sort of foam or alveolar struc- 
ture can sometimes be observed in this substance. 
While the capsule and the structures within it are assuming 
their mature form, the nucleus has become less densely stained 
and settles down upon the capsule like a cap (figs. 52 to 59). 
It becomes thin in the center so that its final shape is that of a 
cup with a rounded, thin bottom and a thickened rim. This 
thickened border fits upon the mitochondrial ring so that in 
the mature spermatozoon it is not possible to distinguish it from 
that ring. 
Protoplasmic rays or pseudopodia develop from the rim of the 
cup. I have been unable to determine whether they arise from 
the mitochondrial substance or from the nucleus. 
The spermatozoon 
We may now consider the structure of the mature sperma- 
tozoon. Figure 61 is a drawing of a spermatozoon taken from 
the seminal receptacle of the female and killed in the vapor of 
osmic acid, then stained with gold chloride after treatment with 
formic acid. We observe the nuclear cup (n.c.) from which the 
pseudopodia (ps.) arise. Inside the cup is the spherical capsule 
(c.) within which there is the capsular cavity (c.c.); and the 
inner tubule (7.¢.) with its cavity divided into the inner tubular 
cavity (7.t.c,); and the outer tubular cavity (0.c.). Running 
through the inner tubular cavity and through the wall of the 
inner end of the tubule to the bottom of the capsule we see the 
central body (c.b.). Figure 62 was drawn from a live sperma- 
tozoon in 4 per cent KNOs, and figures 63 to 65 are from sperma- 
tozoa mounted in the serum of the crab’s blood. Movements 
of the blood have bent the pseudopodia of these spermatozoa. 
Otherwise they have more nearly the natural shape and propor- 
