NEW TYPE OF PROTISTAN PAPASrPE. 
441 
wefc-fixed films. Apparently the somewhat rougher treat- 
ment of the parasites in making a Griemsa smear — perhaps the 
drying — may cause the flagellum, in certain cases, to be 
partially broken up into component fibrils. This observation 
is very interesting, because it points to the flagellum having 
a structure rather different from that of most ordinary flagel- 
lates, for, in the course of our work on the forms which crop 
up in the ftecal cultures (e. g. Monas, Cercomonas, 
Bo do), we have never observed such a splitting of the 
tlagellum, and we have made numerous Giemsa smears.^ 
It is apparent from wet-fixed preparations that a definite 
membrane or envelope surrounds many, if not all, the 
crescents. It is curious that, within a short distance of one 
another, parasites can be found, both single individuals and 
forms undergoing division, which show indications of this 
envelope to a very varying extent. Thus it may be seen, 
standing off from the general protoplasm of the body, only at 
one end (figs. 23, 35, 36) ; or at both ends (figs. 6, 16) ; or 
along one side (fig. 2) ; or nearly all round the body (figs. 3, 19, 
27). In others, again, it is not discernible at all (cf. figs. 1, 4, 
7). We are uncertain whether these different appearances 
represent the actual condition in life, or whether they are to 
some extent due to the body-protoplasm having undergone a 
certain amount of shrinkage away from the envelope in the 
wet-fixation, more especially in the direction of length. As 
mentioned above, no envelope, distinct from the general 
body-substance, can be made out in the living crescents, nor 
is it obvious, as a rule, in the parasites on Giemsa smears. A 
point to notice is that the envelope never stands off from the 
general protoplasm at the point where the flagellum is 
attached; this indicates that the latter organella is not 
merely a development from the membrane, but originates 
' This splitting is never seen in the living parasites, but it is in- 
teresting to note that we have observed a somewhat similar splitting 
of the flagellum (in life) in a “ true ” flagellate occurring in the rumen 
(perhaps a Sphseromonas), which possesses a long, thick, curved 
flagellum. 
