95 
The Evolution of the Higher Uredinece. 
which they stand are determined by the nature of the host rather 
than by that of the parasite. The chief guide in classification must 
always be the form of the teleutospore. Dietel’s “ Rule,” it will 
be observed, is again not broken. 
Puccinis on Adoxa. 
Another case of a highly involved, but slightly different, nature 
must now be considered. On Adoxa Moschatellina in this country 
( a spring flowering plant) there is found an aecidium, accompanied 
by spermogones and sometimes followed on the same plant by a 
few scattered teleutospore-sori which contain also a small number 
of uredospores; this is called P. albescens Plowr. (Fig. 1, H), 
There is also found on the same host a Puccinia (P. Adoxce Hedw. f.), 
m 
which produces only teleutospores in densely crowded sori (Fig. 1, J). 
These two forms appear to be almost always separated: one at¬ 
tacking Adoxa in one district, and the other in another district, 
not only so in England, hut also on the Continent. Moreover, 
these teleutospores ofP. Adoxce begin to appear abundantly in 
early spring (March) at the same time that the secidia of P. albescens 
are appearing in their district, while the few teleutospore-sori of 
the latter do not appear till May. Thirdly, there is a Puccinia 
(P.argentata Wint.) which has its spermogones and secidia on Adoxa, 
but its uredo- and teleutospores (Fig. 1, K) on Impatiens; these 
latter have been found in only one district in this country. The 
hetercecism in this case has been fully demonstrated by Bubak (4). 
The teleutospores of all three are almost exactly alike, and although 
an attempt has been made by Bubdk to distinguish the two secidia 
by the colour of the spores, the distinction is of little value, even if 
not, as 1 am inclined from my experience to think, quite untrue. 
Some authors unite the two former species, but this does not meet 
with general approval, and the most natural conclusion from the 
known facts is that we have here a mutating species which has not 
yet completely specialised itself into three forms—P. albescens , a 
complete autoecious species on Adoxa (Auteupuccinia); P. argentata, 
a Hetereupuccinia on Adoxa and Impatiens-, and P. Adoxce , a 
Micropucccinia on Adoxa. 
The first of these would in that case represent the original 
form, from which the other two are being evolved. In North 
America, an aecidium on Adoxa is found, but the teleutospores are, 
at any rate, excessively rare on that plant (there seems to be only 
one record), while those on Impatiens are common. It appears 
reasonable to suggest that the fungus is becoming specialised as 
hetercecious in North America, where Impatiens is abundant, while 
