440 
H. M. WOODCOCK AND G. LAPAGE. 
the end nearest to which the flagellum is inserted goes flrst 
and may be regarded as anterior^ the flagellum itself being 
directed backwards. 
As regards the dimensions of the parasites, crescents of 
average medium size have a length of 9'5 to 11 /x and a 
breadth of 2 to 3 ^ (Text-flgs. A-D and figs. 1-8, 11-16), 
the length of the flagellum being about 8-9*5 f.i. The largest 
(single) individual we have observed (on a “ wet-fixed film) 
is 12*5 fi long by 3*25 /ul broad and the flagellum is 15 u long 
(fig. 10) j on a (xiesma smear, the largest crescent 
found measures 13*5 /.i in length by 3*75 fi in width,^ the 
flagellum being 12 long (fig. 77). The smallest crescent 
observed, just in the act of separating after division (fig. 33), 
is only 4*25 a by 1*9 fi ; another small one (fig. 35) is 6*25// 
long and rather stouter, being 2*5 g broad. Between these 
extremes all intermediate sizes occur. 
The flagellum itself may be as long as 16 u (fig. 2) or as 
short as 7*5 ^ (fig. 12) ; its length does not bear any very 
close relation to the size of the parasite, the small individual 
of fig. 5 having a very long flagellum, while the large para- 
site of fig. 19 has a relatively short one. A remarkable fact 
bearing upon the structure of the flagellum is brought out by 
‘^dry Giemsa-staiued smears. In wet-fixed films the flagel- 
lum does not apparently differ much from that of an ordinary 
flagellate ; it has, perhaps, a thicker and stronger appearance 
on the whole, though it usually thins out a little and becomes 
more tapering towards the free end. On Giemsa smears, how- 
ever, the flagellum is frequently seen to be more or less 
broken up into separate bands or fibrils, often throughout the 
greater part of its length (figs. 75—77) ; or else it has split 
into two or three fibrils near the free end. This appearance 
has certainly nothing to do with division, which is quite 
different (cf. below) ; moreover, we have never seen it in 
* Some of the pai’asites on Giemsa smears are possibly a little too 
wide relatively, having been flattened ont slightly in making the prepa- 
ration ; on the other hand, the parasites on wet-fixed films are probably 
slightly (uniformly) contracted. 
