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New Protist Parasites 
III. Description. 
(1) 'The living parasite. 
Trichomastix trichopterae is of approximately pear shape, with average 
dimensions of 8'op x 3/t. There is great diversity in size, however; 
some large individuals measure as much as 12'8p. in length, and there 
occur minute forms of only 5/r. From the anterior end arise four long 
flagella, of which three are directed forwards, and one backwards as a 
sort of “ Schleppgeissel.” They are all rather longer than the organism 
itself, but the “Schleppgeissel” is generally the longest. The point of 
origin of the flagella is a highly refractive granule situated in the 
flexible prominence that slightly overhangs the cytostome. The “stalk” 
of the pear is formed by the axostyle, which pi’ojects from the posterior 
end, and can be traced up for a considerable distance within the body 
as a refractive rod. The projecting portion is frequently as much as 
7 g long, or more than half the total length; it would seem to be longer 
in proportion here than it is in other species. Sometimes it is much 
reduced, or may occasionally be altogether absent. It can be seen that 
the axostyle is clothed by a layer of cytoplasm of somewhat unequal 
thickness: the appearance reminds one strikingly of the axopodia of the 
Heliozoa. In Trichomastix trichopterae the axostyle, while no doubt 
partly skeletal in function, is also used as an organ of attachment. In 
this respect it differs from the axostyles in T. serpentis and T. batrachorum, 
which, according to Dobell, are purely skeletal 1 . If the intestinal 
contents of a larva be teased out and examined in vivo, many of the 
trichomonads will be found attached by the tip of the axostyle to 
clumps and tangles of bacterial matter. Anchored thus, the organism 
lashes steadily with its flagella, and drives a current bearing food- 
particles forwards in the direction of the cytostome. This is quite the 
normal state of affairs, as may be proved by watching the flagellates 
moving inside the gut. The cytoplasm clothing the axostyle is slightly 
viscous, especially towards the extremity, to which small masses of 
bacteria and debris can often be seen adhering. At times the organism 
writhes slowly about among the tangles of Streptothrix where the 
flagella have not free play, and the forward progress seems to be effected 
by “ euglenoid ’’-like movements of the body. Under unfavourable 
conditions, such as pressure from the cover-glass, I have seen the 
1 In the Trichomonas from the mouse, Wenyon (1907) describes the axostyle as an 
organ of temporary fixation. 
