102 
Helicosporidium parasiticum 
However, a further study of the parasite showed this supposition to be wrong, 
for the spores above described were found to undergo further development 
in the dead body of their host. 
4. Development of the spores subsequent to the death of the host. 
The decomposing sap collected from the wounds of trees often contains 
dead Dasyhelea larvae which, on microscopic examination are found to be 
completely filled with elongated filaments 60-65 /x long, with pointed extrem¬ 
ities (PL Y, figs. 8 and 9). As these filaments show a close resemblance to the 
acicular spores of yeasts of the genus Monosporella, one species of which I have 
described as being parasitic in the larva of Dasyhelea , I was at first under the 
impression that the elongated filaments were the spores of a similar yeast. 
Subsequent observations showed me that such was not the case. These 
filaments have nothing to do with yeast, but actually belong to a later phase 
of the development of the spores of Helicosporidium. I have been successful 
in tracing the consecutive steps in the formation of these free filamentous 
structures from the barrel-shaped spores. If we isolate a parasitised Dasyhelea 
larva in a drop of ordinary tap water or in a small quantity of decomposed 
sap and leave it to itself it will soon die, being killed by the parasite. On 
allowing the body of this larva, filled with the barrel-shaped spores, to dry 
very slowly no noticeable change will occur in the spores; but if the dried body 
is moistened again; it swells up and a large number of filaments similar to 
those we have previously mentioned will appear among the barrel-shaped 
spores. The formation of these filaments does not necessarily result from a 
previous drying; it may occur also in the parasitised larva continuously sub¬ 
merged in water, but in this case the process takes place much more slowly. 
The successive drying and moistening of the spores appears, however, to 
hasten the formation of the filaments, and doubtless plays a very important 
part in nature, because the wound of the tree is necessarily exposed to alter¬ 
nating conditions of drought and moisture. 
All the stages in the formation of these filaments are easily found by 
opening the body of the parasitised larva in a drop of water a few days after 
the insect’s death (Text-fig. 2). The process whereby the barrel-shaped spore 
gives rise to filaments can only be followed, however, by examining smears 
prepared from the dead infected larvae, fixed with Schaudinn’s solution 
and stained with iron-haematoxylin. 
Such smears show very clearly that the filaments are the unrolled internal 
spirals liberated from the spores. The latter, under the pressure of the unrolling 
spirals, rupture at one end, and from the opening in the ruptured sporocyst 
a portion of the spiral protrudes (PI. IV, figs. 42-47). The protrusion usually 
begins at one end of the spiral, which progressively unrolls and liberates 
itself from the sporocyst. At various stages of this unrolling the three central 
round cells are mechanically expelled from the spore, leaving the sporocyst 
completely empty. 
