34 H. B. FANTHAM. 
The membrane! of 8. anodonte (PI. 2, figs. 27, 29, 30, 
31,32; Pl. 3, fig. 39) is most difficult to discern and to stain, 
more so than that of 8. balbianii. In both cases, a mem- 
brane is undoubtedly present, sometimes very narrow in very 
attenuated forms (cf. Pl. 3, fig. 23). The structure of the 
membrane of S. anodontz conforms to that described for 
S. balbianii, namely, a matrix of hyaline, viscid protoplasm 
directly continuous with the periplast of the body, and 
strengthened by a number of almost longitudinally arranged 
myoneme threads (PI. 2, figs. 27, 29). 
The chromatin border of the membrane is stated by Perrin 
(9) “to be continued into a fine line ending in a dot, which 
is connected with the nuclear band” at one end. Swellen- 
erebel (10) mentions that this border sometimes commences 
ina granule. This is very difficult to observe. I have some- 
times seen such a dot, but only at one end, not at each end, as 
one might expect from the ease and frequency with which 
these organisms suddenly reverse their direction of motion. 
Such a dot may be termed a “ centrosome” (PI. 3, fig. 22). 
Closely connected with this in 8. balbianii is the occur- 
rence at the extremity of each of the rounded ends of a larger | 
dot or granule of chromatin (Pl. 1, figs. 5, 5a; Pl. 2, fig. 27), 
“the thickened nodules of periplast”’ of Perrin (9). Hach of 
these dots divides into two smaller dots, lying side by side, in 
parasites about to divide (Pl. 3, figs. 19,40). These dots stain 
red with Giemsa’s solution, and are deeply coloured by gentian- 
violet or iron-hematoxylin. They are, I think, composed of 
chromatin and are ‘ basal granules” comparable with those 
occurring in Trypanosomes, as described by Schaudinn (20) 
Tome ano. tines. 
The ends of 8. anodonte are tapering, not rounded as in 
S. balbianii, and each tapering end appears, with Giemsa’s 
stain, as a red thread, about 4 long (Pl. 3, fig. 87). At the 
1 Through the kindness of Professor G. H. F. Nuttall I have been enabled 
to examine a stained preparation of S. duttoni. I believe it possesses a 
narrow membrane, which has not been recorded before, but I should like 
further material to make quite certain. 
