224 
A Myxosporidian 
THE AMOEBULA. 
When fresh spores are brought into contact with the gastric fluid of the 
frog either in a hanging drop preparation or in the host’s body, the following 
changes take place. The two sporoplasms increase gradually in size, and 
seem to fuse into a single mass along the surface of contact (Fig. 1). The 
amoebula shows very slow amoeboid movements, and appears to press the 
polar capsules against the anterior margin of the spore membrane (Figs. 1-3), 
which results in the extrusion of the polar filaments through the foramina. 
This condition was noticed only in gastric fluid or weak pepsin hydro¬ 
chloric acid. In all other cases where the extrusion of polar filaments took 
place under the influence of reagents, such as potassium hydrate, lecithin or 
sodium glycocholate, the extrusion was more quickly brought about than 
in the case mentioned above, and no visible change occurred in the sporo¬ 
plasms. 
A similar movement of the amoebula inside the spore membrane prior 
to its emergence, seems to have been noticed by Auerbach (1910) in the case 
of Myxidium bergense. 
After some time, the shell-valves become separated first at the anterior 
half (Figs. 4, 5) and then along the entire sutural plane (Figs. 6, 7). The 
amoebula was frequently seen making its way through this opening to the 
outside of the spore. The movements are very slow, yet can distinctly be 
followed in hanging drop preparations. When kept at 20° to 25° C., numerous 
amoebulae and empty spore membranes were noticed in the preparations after 
6 to 24 hours. Similar changes to those stated above, were further noticed 
in spores treated with a mixture of gastric fluid and bile, and with the fluid 
taken from the duodenum. But no change was visible in the spores mixed 
with the fluids taken from the large intestine and with the urine. On the other 
hand, the action of weak pepsin hydrochloric acid upon the spores was similar 
to that of gastric fluid. The physiological solution and solutions of lecithin and 
sodium glycocholate did not cause any further change than the extrusion of 
the polar filaments. 
The liberated amoebula moves about very slowly. Its nuclei cannot 
distinctly be made out in the fresh state, although not infrequently they were 
seen as faintly outlined bodies (Figs. 3, 5). The cytoplasm does not show any 
distinct differentiation either in the fresh state or when stained. In the 
fresh state, it appears to be composed of homogeneous substance with three 
or more spherical granules of variable size. Figs. 8 and 11 show most probably 
one and the same amoebula. In this preparation, five spores were mixed with 
a drop of the gastric fluid after separating them from the others by means of 
serial dilution. The amoebula shown in Fig. 11 was moving about sluggishly 
after leaving the spore membrane. The cover glass was fixed and stained. 
Judging from its position upon the stained preparation, the amoebula shown 
in Fig. 8 is, in all probability, identical with that shown in Fig. 11. 
