98 Church . — The Polymorphy of 
The observations made at Plymouth suggested that Aglao- 
zonia vegetated at an optimum of io°-i2°, but was perennial 
within the annual range of 6°-i 8° ; the zoospores germinated 
in the spring at 12 0 , and the optimum range of temperature 
for Cutleria was from I2°-i6° 5 this being accompanied by the 
great light-intensity of May and June. Under these con- 
ditions the thallus was mature and in full reproduction in 
four months, of which one month may be included in the 
protonematoid embryo stage. It died (in the Laboratory) at 
20°, this temperature being reached at the end of August in 
shallow enclosed water, and also on the autumn fall to 13 0 . 
The autumn fall to T2°, although accompanied by great 
diminution in light in October and November, led to re- 
newed growth of the Aglaozonia which perennated through 
the winter, growing slowly at its optimum temperature, but 
stopping if the light-supply was slight, as in dull weather in 
November and December. The same conditions were also 
fatal to the whole of the foot-embryos in all stages, which 
had not yet thrown out Aglaozonia expansions. 
Complete data are not available for Naples , but the same 
annual period of maximum and minimum obtains, the range 
being from 8° in January and March to 27° in July and 
August. As before noted, temperatures to have more than 
an approximate value require to be taken where the Cutleria 
is growing, and as Berthold gives temperatures of 15° and 17 0 
for February and December, it would seem that Cutleria lives 
in these waters under similar temperature-conditions to those 
which obtain in the Channel in summer; i.e. it commences 
growth on the autumn fall in December and matures in four 
months, completely disappearing in shallow water in April, 
as the temperature rises to near 20°. At the same time the 
Aglaozonia is perennial over the summer heat of 27 0 , or at 
any rate may exist in deeper and colder water. According 
to Berthold, a stunted growth of Cutleria also occurs in deep 
water in July and August to a certain extent, the temperature 
at the depth of growth, forty fathoms, being I4°-I7°, thus 
approximating the English temperature. This growth appears 
