26 H. B. FANTHAM. 
Deraitep MorpHouocy. 
As stated, the attenuated body of these organisms con- 
sists of a clear cytoplasm surrounding a spiral granular band ~ 
of chromatin. The cytoplasm usually appears homogeneous, 
but in favourable specimens an inner, slightly more granular 
layer can be seen, which is the endoplasm and surrounds the 
nucleus. 
Cytoplasm. 
The outer layer or ectoplasm is clear, and generally entirely 
converted intoa periplast. In some specimes of Spirocheta 
balbianii kindly stained for me by Dr. A. C. Stevenson with 
Billet’s modification of the Giemsa stain (namely, carbonated 
blue added to methylene-azur and eosin), the outermost layer 
of the body, that is, the external portion of the periplast, is 
coloured red, and shght dots appear along it (PI. 38, fig. 19, my.), 
giving it a beaded appearance. These dots may be merely a 
staining artifact, but personally I think they are not artifacts, 
but represent a normal structural feature of the organism, 
namely, the presence in the outer portion of the periplast of 
contractile fibres (myocyte fibrille or myonemes). Dutton 
and Todd (quoted in [24, p. 210]) mention an apparent 
ectoplasmic structure in Trypanosoma mega staining 
pinkish with the Romanowsky stain, and showing myoneme 
structure. I think there is a myoneme-containing layer in 
the periplast of Spirochetes (vide Pl. 1, figs. 2, 5a, 11, 
my.), and the dots (Pl. 3, fig. 19) found therein—giving 
it a beaded appearance—may be the visible result of con- 
traction or may be portions of a very fine and practically 
invisible meshwork of contractile elements, comparable to the 
network of myocyte fibrille of Gregarines, which are often 
more or less circular in many of these Sporozoa; but in the 
Selenidiide the fibrils are longitudinal and beaded during 
contraction, and are, indeed, thread-like myonemes. Further, 
Perrin stated that the periplast contained fibrils, judging 
