204 Transactions British Mycological Society. 
ORIGIN AND DEVELOPMENT. 
A brief account of Dr Church’s views on the origin of lichens 
from skinned sea-weeds was given in an Appendix to Lichens 
(Ig21). Since then several other weighty papers packed with 
facts and with reasoning have appeared: it is not possible to 
do more than indicate the trend of his argument. He thus 
summarizes the stages from stranded alga to heterotrophic 
fungus-lichens. 
“(1) The alga accustomed to a moving aqueous environment 
finds itself in standing pools of sea-water, and the failure of 
oxygen-supply is the most readily conceivable cause of the 
death of the autotropic surface tissues thus leaving the thallus 
penetrable (a skinned alga). 
(2) Competition for substratum gave the mantle of green in- 
trusive gonidia of the type of Chlorella. 
(3) The associated plants in subsaturated air obtained more 
oxygen and grew more freely. 
(4) The nitrogen-problem still keeps the plants impoverished. 
(5) The water-problem tends to keep them small and re- 
stricted to short seasonal periods, thus further delaying the 
rate of growth.” 
Again: “ Lichens of to-day constitute one of the pioneer races 
of the older world, on the first rock-surfaces exposed above the 
retreating sea; and they have held their station to the present 
time, since no other plant organism can compete with them in 
endurance on such a feeble food-supply.”’ 
In the lichen life-cycle, he traces the parallel history of the 
origin of the mechanisms of the reproductive organization which 
are always considered to represent racial continuity. He finds 
that spermatogamy (fertilization by a sperm or spermatium), 
now vague for the Ascomycetes as a whole, is undoubtedly the 
dominant method for Lichen-Fungi, as it is also a biological 
process for securing cross-fertilization, and is undoubtedly of 
strictly marine origin. Church contrasts this with the still 
operative fertilization of the Rhodophyceae. He considers fungi 
and lichens as relics of a very old race and that “‘in Ascomycetes, 
lichen fungi and Laboulbeniaceae may be traced such suggestion 
of Pre-Floridean or Para-Phaeophycean phyla.” “It is the 
quiet pool that is now the characteristic habitat of Florideae 
and all spermatogamic races must have passed through the 
same environment.” 
These few quotations give merely the barest outline. There 
is much with which one is in agreement, but much also that 
one does not accept. For instance he considers the Floridean 
carpospore as homologous with the ascospore as both are 
produced in closed bodies. There we entirely disagree, and 
