D. Keilin 
103 
In somewhat rare cases the protrusion of the spiral begins either with a 
loop (PI. IV, fig. 44) formed by its central portion or with both extremities 
simultaneously (Fig. 46). 
The same smears also contain many other spores devoid of a sporocyst 
(Text-fig. 3). The spiral filament of these spores is of a very irregular shape, 
the rings which form it being often loosened or the unrolled portion secondarily 
twisted. The irregular form of these filaments is undoubtedly due to mere 
mechanical pressure produced during the preparation of the smears. 
Text-fig. 2. A drop of fluid taken from the dead body of a Dasyhelea larva infected with Helico- 
sporidium. The drop diluted with normal salt solution, shows different stages of the opening 
of the spores and unrolling of the spiral filaments. 
The three liberated central cells, which are 2p in diameter, remain much 
as they were when inside the sporocyst, with the difference that the refractive 
granules in their protoplasm are now more distinctly visible. 
The structure and size of the filament are fairly uniform. Examined in 
vivo they are straight, needle-shaped (Text-fig. 2 and PI. V, figs. 8 and 9), 
60-65p long and 1/x wide. They are very refractive, pointed at both ends, 
but the two extremities are not equally attenuated. 
In fixed and stained smears, these filaments are more or less sinuous and 
much narrower, not exceeding 0-65p in their widest portion (Text-fig. 4, 
PI. Y, fig. 7). This is undoubtedly due to the fact that the central axial 
