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they consider it an argument in favor of the thallus nature of the 
podetium. In his description of them, the author says on the 
periphery of the fruit body there is often an entire mantle of 
these gonidia with their hyphz threads, in other cases they are 
in little heaps. By following the development of these lichens it 
is seen that there is no possibility of these gonidia having origi- 
nated from those in the thallus. This being admitted, there are 
only two other hypotheses possible. Either they must be the di- 
rect product of the hyphce threads cut off by abstriction, or they 
must be foreign bodies which have found their way there from 
outside, and have clung there till the hyphz on the outer part of 
the lichens have woven them in. The former hypothesis is un- 
tenable on the grounds that such a formation has never been ob- 
served, and this forms a strong argument for the fungus-alga 
theory of the lichen. If the gonidia were a direct outgrowth of 
the hyphz threads they must have been found in the process of 
development. This leaves only one explanation, namely, that 
they are foreign bodies which have been borne to the podetium 
through the air. The author says there are many other indica- 
tions of such an origin, and then discusses the question whether 
these little bodies come to the lichen already clothed with their 
hyphz filaments, that is, as complete full grown soredia, or sim- 
ply as naked alge cells which afterward receive their covering 
from the lichen. He decides in favor of the former supposition, 
as only in two cases were naked algz cells found on the lichen, 
and it was difficult to determine their fate. It was found that 
the outside surface of the podetium was loose in texture and 
thickly beset with little hooks curving over so that on the arrival 
of the soredia they were taken hold of and held fast, while the 
hyphe threads from both soredia and podetium surface twine 
and interlace till complete union is formed. The philosophy of 
this curious arrangement is very evident. The podetium in its 
development grows by apical and intercalary growth in such a 
manner as to be unable to carry up the little providers of carbo- 
hydrates from the thallus below. So this lack is supplied from 
without apparently, in a purely accidental manner. There is 
however, no more indications of accident than in many other in- 
stances, as, for example, pollination by wind-carried pollen 
grains. 
