112 
Helicosporidium parasiticum 
EXPLANATION OF PLATES IV—VI. 
Helicosporidium parasiticum. 
PLATE IV. 
All the figures of this plate relate to the smears fixed in Schaudinn’s solution with 1 per cent, 
of acetic acid added, and stained in iron-haematoxylin and eosin. Owing to the small size and 
complicated structure of the spores, high magnification was used for this study: Apochromatic 
imm. object. 2 mm.; N.A. T4 with Comp, oculars 8 and 12. For the sketches which were made 
with the camera lucida, comp, ocular 18 was used; the scale of magnification common to all the 
figures is shown in the plate beneath the figures. 
Figs. 1, 2, 3. Trophic stages of parasite. 
Figs. 4, 5. First division of the parasite and formation of two cells. 
Figs. 6-9. Different forms of bicellular stage. 
Figs. 10-12. 2nd division and formation of schizonts of four cells. 
Figs. 13, 14. Schizonts composed of four cells, tetrahedrally disposed. 
Fig. 15. Exceptional forms of four cellular schizonts with merozoites radially disposed. 
Figs. 16, 17. Breaking up of four-celled schizonts into four merozoites. 
Fig. 18. Nuclear division in schizonts of four cells. 
Figs. 19, 20. Schizonts composed of eight cells. 
Figs. 21, 22. Breaking up of eight-celled schizont into eight merozoites. 
Figs. 23, 24, 25, 26. Three successive stages in formation of‘morula of four cells tending to forma¬ 
tion of the spores. 
Figs. 27, 28. Further transformation cf these cells showing one cell growing more rapidly and 
surrounding the three other cells. 
Fig. 29. Obscure stage showing a central mass surrounded by a ring. 
Fig. 30. Hypothetical figure showing the three central discoidal cells surrounded by the fourth 
cell. 
Fig. 31. A young spore, end view, showing a central darkly stained body composed of three 
superposed discoidal cells, surrounded by a very refractive ring, and by a thin wall or sporo- 
cyst. 
Fig. 32. Side view of a similar spore showing clearly the three central cells. 
Fig. 33. Further development of the spore (as shown in Fig. 32), showing the spiral filament 
formed in the refractive ring surrounding the three central cells or sporozoites. 
Figs 34-37. Spores viewed side-wise, similar to that illustrated in Fig. 33, showing some variation 
in size (due to fixation) and in the appearance of nuclei of the central cells. 
Figs. 38-40. End view cf a similar spore, the figs. 39 and 40 do not show the sporocyst, this 
being due to contraction by the fixative. 
Fig. 41. Spore stained and much decolorised, showing a nucleus in the spiral filament. 
Fig. 42. Spore seen from one end in a smear where almost all the other spores are already open 
(derived from the dead larva). 
Figs. 43, 44. Ruptured spores showing the protrusion of a portion of the filament. 
Fig. 45. Protrusion of the filament through the opening of a ruptured sporocyst. 
Fig. 46. A case of protrusion of both ends of the spiral filament. 
Fig. 47. More advanced stage of protrusion of the filament and its unrollment. 
PLATE V. 
Photomicrographs taken by Mr L. E. Robinson. 
Fig. 1. Living larva of Dasyhelea obscura heavily parasitised, pressed between the slide and a 
coverslip until the posterior end of its body was ruptured, projecting an enormous mass of 
spores. The latter can be seen still filling the body cavity of the larva and reaching into the 
head. x 75. 
Fig. 2. The upper portion of the same larva under a higher magnification. x 150. 
Fig. 3. Another larva, filled with spores of Helicosporidium and ruptured in its middle, showing 
the spores inside and outside the body. x 150. 
Fig. 4 x 800. Fig. 5 x 300. Fig. 6 x 250. Fig. 7 x 500. Fig. 8 x 100. Fig. 9 x 400. 
