1916] FoMES OFFICINALIS (Vill.) 201 
reaches its maximum. Here the threads run radially, closely packed, 
and with little branching. A common type of branching is illustrated 
in Fig. 22. One of the strangest features is the fact that the thin-walled, 
much-septated threads are by far the most abundant, and the secretion 
of resin is so great that a solid matrix results, in which in untreated 
sections of fragments they are wholly indistinguishable. Fig. 21 is a 
drawing of a fragment 120 thick, from which a few thick-walled hypha 
are shown projecting; the mass, however, is made up of thin-walled 
threads arranged parallel and closely packed. By treating a section 
with a few drops of alcohol the resin is dissolved out and the structure 
becomes discernible. The resinous crust is extremely brittle, and friable. 
An examination of the crust of the sporophore revealed another 
feature of unusual interest, namely, that here there is a formation of 
chlamydospores, especially in older parts of the fructification, and some- 
times so abundantly as to constitute a fairly continuous layer (Figs. 18, 
a-c). They are formed in chains, from septated threads by a further 
septation, with or without enlargement, followed by a thickening of the 
walls. They vary in size from 2-7 X2-6u, in shape from irregularly 
spherical to elongated, and in colour from hyaline to yellowish brown, 
the colour in the latter case appearing only as the spore matures; the 
threads from which they are successively formed in basipetal order are 
commonly purely hyaline. It is quite obvious that the friable nature 
of the sporophore, so great at the surface as to be readily worn by 
weathering, is an advantage in their distribution. 
Two explanations now may be advanced in explanation of the occur- 
rence of these spores, namely that they are a secondary means of repro- 
duction, or that they are the product of another fungus, either an 
invader or a symbiont. That the first is the correct interpretation is 
borne out by a number of observations. They were found to occur in 
all the older fruiting-bodies which I have examined—from two localities 
in British Columbia, and from two in Ontario, widely separated in each 
case; they are found in radial chains, often in abundance, in the resinous 
crust, which would appear to be a barrier against invading fungi; they 
were found in my artificial cultures; and they are known to occur in 
the fruiting-bodies of certain other polypores, including Polyporus 
sulphureus, a species which shows resemblances to F. officinalis in other 
respects as already noted. The possibility of a commensal arrangement 
is, of course, not excluded, a theory, however, which was proven to be 
incorrect in the somewhat similar case of Nyctalis, for the chlamydo- 
spores on being sown produced the normal Nyctalis fructification, and 
cultures from the basidiospores of Nyctalis bore the same type of chlamy- 
dospores (Krombholz®; Brefeld!; Costantin‘). 
