The Evolution of the Higher Uredinece. 91 
To explain this state of things it was suggested that there was 
originally a complete autoecious species of Puccinia which had its 
spermogones, aecidiospores, uredospores and teleutospores on 
Anemone. From this, we may suppose, there could arise (1) a 
species of Micropuccinia on the Anemone with teleutospores only, 
the other two useful spore-forms being suppressed, but the useless 1 
spermatia still lingering as a survival or legacy from the past, (2) a 
species which still retained its spermogones and aecidia on Anemone 
but which had transferred its uredo- and teleutospores, by a sudden 
mutation, to various species of Primus. 
Putting aside, for the moment, the consideration of the 
reasonableness of the suggestion, the possibility of such an evolution 
cannot be gainsaid. The mutation is possible, because the 
aecidiospores, being produced in enormous numbers at a certain 
period, must be spread over all the leaves of plants belonging to 
the same association within a certain radius; there they might 
germinate, the germ-tube would penetrate through a stoma if it 
could, and having once gained access to the stores of nutriment 
contained in the cells within would draw upon them for its food 
supply, if their mutual chemical and vital attractions and repulsions 
would permit it to do so. Untold millions of Eecidiospores go through 
this experience annually, and untold millions fail;'but that is no 
reason why, at rare intervals, when every circumstance is favour¬ 
able, one of them should not succeed in establishing itself upon the 
new host. It is known that the aecidiospore is rejuvenated by the 
effect of the presence in it of two non-sister nuclei, and as Olive 
says (20) we should expect the hetercecism to arise, if at all, just at 
that point of greatest vigour. It is also known that germ-tubes 
can enter the stomata of plants other than their proper hosts (13): 
their further growth would demand a certain chemical affinity in 
the cell-contents of the two hosts, and probably also a slight change 
(mutation) in the cell-contents of the spore itself, such as we know, 
from Marshall Ward’s experiments on Puccinia dispersa, to occur 
at intervals. 
So far, however, this is mere supposition : but there is more 
to follow. If the imagined autoecious species on Anemone ever 
existed, it might still remain, in some corner of the world, if not in 
Europe. There is a very rare species, first described in 1902, on 
Anemone decapetala in Texas but found nowhere else, which answers 
1 All the numerous attempts that have been made to convey infection by 
means of the spermatia have uniformly failed. 
