8 
Harper and Dodge . — ■ The Formation of the 
about to begin, they are common. The smaller nuclei here may well be 
young daughter nuclei as suggested. The appearance of some of them, 
however, really suggests that they are degenerating. They are also not 
conspicuously distributed in pairs, as they might be expected to be if they 
had just been formed by division, and they are more variable in size than 
might be expected if they represent the same telophase stage. 
In their mature condition the spirals are somewhat more strongly 
developed than they are at the stage shown in Fig. 5 , but the main difference 
is due to the shrinkage which has taken place in the ripening and drying out 
of the whole sporange. As a result of this drying the lumen of the capilli- 
tial tube is quite small, so that the structure of the thread appears to 
be almost rope-like. The spores are at first uninucleated and thin walled. 
With the full development of the thickened and sculptured spore-wall the 
fixation and staining of the nuclei becomes more difficult. 
The formation of the capillitium in the Slime-moulds is in many respects 
a unique process. As noted in their shape and surface markings the capilli- 
tial threads of many forms suggest the elaters of the Liverworts. They are, 
however, in no sense modified cells — the spiral and other types of thicken- 
ing are on their external surfaces. The nearest analogy to the conditions 
under which they are formed is perhaps to be found in the relation of the 
periplasm to the formation of the epispore in the Oomycetes. In both cases 
we have to do with a multinucleated protoplast which produces in some way 
a symmetrically sculptured wall about another centre than its own. Little 
is known as to the real nature of this process by which the epispore is laid 
down, further than that, as was first shown by de Bary and Strasburger (42), 
the process is centrifugal from the oospore as a centre just as it is in 
the case of the formation of the perinium in the Water Ferns. The peri- 
plasm disorganizes in building the epispore, while the spore-plasm of the 
Slime-moulds proceeds at once to cleavage and spore formation. 
The deposit of materials in the vacuoles from which the capillitial 
thread is formed may properly be called a process of intraprotoplasmic 
secretion, and is no doubt similar to that by which other soluble materials 
are deposited in the cell-sap of vacuoles, and may then crystallize out if the 
solution becomes sufficiently concentrated. Such crystals are regularly 
formed in the vesicular nodes of the capillitium of Tilmadoche , Physarum , 
and other types, as noted above. It is hard, however, to think of the 
formation of the spirally sculptured capillitial thread as caused simply 
by crystallization. We have here an adaptive morphogenetic process of 
the same type in these respects as we have in the formation of specially 
thickened and sculptured cell-walls. There seems to be no question also 
that the wall of the thread is built by appositional growth, though it shows 
no laminated or stratified structure. 
In the fact that a multinucleated mass produces in its interior sym- 
