FURTHER OBSERVATIONS ON CiECAL PARASITES OF FOWLS. 73 
paratively short period that we feel that any objection on 
this score can carry relatively little weight. On the other 
hand, we can certainty find no evidence in this form that 
the axostyle plays the important part in the division of the 
nucleus which has been assigned to it by some workers on 
allied forms. 
The later stages in division are shown on PI. 12, figs. 43, 44. 
In addition to the active forms of Trichomonas Ebert hi, 
relatively rare true resting forms are also met with. 
A typical restiug form is figured (PI. 13, fig. 45), in which 
the nucleus, blocks and well-developed chromatic line are 
quite normal, but there is no trace of the flagella. These 
forms are in life characterised by a peculiar movement, 
during which a conical wave of protoplasm travels slowly at 
regular intervals down one side of the animal. Every stage 
can be found between such a resting form and the active 
Trichomonas witli its three anterior flagella and well-developed 
membrane. In the form figured on PI. 13, fig. 46, the mem- 
brane is well developed, and in the presumably later stage, 
figured in fig. 47, an axostyle is also present. 
Part of the changes between such a form as is figured 
in PI. 13, fig. 48, and the typical active form have been 
followed on the living animal. The new free flagella are split 
successively from the edge of. the undulating membrane (cf. 
PI. 12, fig. 34). 
The new free flagella thus formed at first trail behind the 
animal, and it is to this fact we believe that the difference 
in movement so often observed in these Trichomonads is due. 
In the fully developed Trichomonas the free flagella strike 
successively well out in front of the animal, whereas in the 
trailing form the free flagella drag behind the animal, and 
the whole movement of translation is probably due to the 
action of the undulating membrane. 
As to the origin of these resting forms, it would be 
hazardous in the present state of our knowledge to speculate; 
but we should like in this place to draw attention to another 
well-marked but little understood series of forms which 
