7 6 
Church. — The Polymorphy of 
which are regarded as possibly representing evolutions of 
alternation, in existing groups of Green and Red Algae, 
parallel to that which has reached such a degree of com- 
plexity in the Archegoniatae ; as from its presenting, within 
the limits of a very narrow alliance, a sudden transition 
to a true alternation from the simpler life-history of the 
homotype genus Zonardinia . 
Falkenberg showed, beyond all doubt, that Aglaozonia 
plants were normally the ultimate product of sexual repro- 
duction in Ctitleria midtifida ; but, owing to the death of 
his plants, the question as to the subsequent relations of 
the Aglaozonia to Cutleria — whether the latter arose from 
spores, or was the result of merely vegetative reproductive 
processes — was left open ; as was also that of the strictness 
of the alternation on the side of the perennial and more 
widely distributed Aglaozonia. 
Although the following observations, made at the Marine 
Biological Laboratory at Plymouth, cannot be regarded as 
finally solving the problem, it is hoped that they may con- 
tribute to a more complete acquaintance with the life-history 
of these plants. 
Both Citleria and Aglaozonia grow in the estuary of 
the river Yealm, near Plymouth, at 2-3 fathoms below 
low-water mark, and may easily be obtained, at all states 
of the tide, by dredging. Cutleria grows as a summer annual, 
reaching its maximum development in July and the beginning 
of August. It rapidly diminishes in quantity in September, 
and has completely disappeared by October. Aglaozonia , 
on the other hand, is perennial, growing on stones and shells, 
especially oyster-shells, in the same locality and depth, 
reaching its finest development in October and November. 
Poor in quality during the winter-months, possibly owing 
to its being eaten by Mollusca & c. in the absence of other 
vegetation, it recovers in the spring, and bears reproductive 
sori in March and April. It is also usually in poor condition 
throughout the summer. From these data, it would appear, 
therefore, that in English waters Cutleria is a rapidly- 
