172 
E. A. MINCHIN AND H. M. WOODCOCK. 
body, principally in the direction of length ; at the same time 
the aflagellar prolongation becomes conspicuously developed. 
A regular series of intermediate stages is seen, for example, 
in figs. 4, 18, 17, 6 and 19. The dimensions of these indivi- 
duals are as follows : Fig. 4, (a) total length 35 /x, ( b ) width 
2 h fi, (c) free flagellum 11 jx, ( d ) aflagellar part 4 ju; fig. 18, 
(a) 40 g, (b) 21 p, (c) 16 g, (d) Sfx ; fig. 6, (a) 39^, (b) 3 
(c) 9J/x, ( d ) 5 /i ; fig. 17, (a) 42 ( b ) 3b /u, (c) 12 /x, '(d) 4 g ; 
fig. 19, (a) 43 fj., {b) 4 /x, (c) 11 /x, (d) 5J/x. It will be noticed 
that the length of the free flagellum may vary not inconsider- 
ably and apparently indiscriminately in these forms. This 
point was referred to in describing the cultural forms of T. 
f ring ill in arum ; and we think it is most probable that the 
explanation given in that case holds here also, namely, that 
the different length of the flagellum in what are otherwise 
similar individuals is chiefly the result of the unequal splitting 
of this organella in dividing parasites. 
In T. f ringillinar um, it may be remembered, certain of 
the small forms occurring in the bone-marrow, which were 
broader and more stumpy than the others, were found show- 
ing unmistakably commencing division (cf. fig. 54 of the 
earlier memoir). Hence, as regards the corresponding small 
forms from the little owl, it is most likely that they also 
divide by binary fission, although apparently most infre- 
quently. We have not been able to secure as marked indica- 
tions of the process as were obtained in T. f ringillin ar um, 
but we have found individuals which are broader or stouter 
than the rest, some of which showed the kinetonucleus 
double (fig. 16). .Just as in the case of the chaffinch-parasite, 
these 'small trypanosomes are the only type of form in which 
we have been able to find even a hint of binar}^ division. 
Next, with regard to the large “ blue ” parasites, these also 
can be undoubtedly linked up to medium-sized, slender forms 
by intermediate stages, such as those shown in figs. 9 and 
23. The measurements of these two individuals are as 
follows: Fig. 9, length 43 /jl, width 3 £ /x, free flagellum 7 /u, 
aflagellar prolongation 8 /u ; and fig. 23, length 39 fi (at 
