84 Church . — The Polymorphy of 
parthenogenetic spores had proceeded at a rate equal to and 
with results in a given time identical with those observed in 
the first culture of August 11, and in which the possibility 
had not been eliminated that fertilized oospheres might have 
already become attached to the plants before they were 
gathered. That oospheres did this in the natural state was 
observed on specimens dredged in September, but it is clear 
that continued crops of free-swimming oospheres, germinating 
at the surface, were beyond suspicion. It is also of interest 
to note that the old plants which continued to give these 
crops of germinating oospheres had been, since the middle of 
September, in a rapid state of disintegration, and by 
November 1 were but partial skeletons compared with the 
perfect summer-plants ; nor, at this time, would they have 
been found by dredging. No Cutleria was dredged at 
Plymouth in 1896-97 after the middle of September, the 
plants then evidently decaying and easily losing their point 
of attachment. 
The general result of these observations, therefore, is not 
only to confirm the original observations of Thuret and 
Crouan, made on the opposite shores of the Channel, as to 
the absolute constancy of parthenogenetic development of the 
oospheres at the end of the summer ; but, bearing in mind 
the equal constancy of fertilization observed by Reinke and 
Falkenberg in early spring at Naples, it further leads us to 
correlate the apparent contradiction of these observations with 
the fact that the conditions of external environment are so 
widely different in the case of plants growing in the 
Channel and in the Bay of Naples respectively ; and further 
to suggest that the parthenogenesis of the Channel plants 
may be due to the fall of the temperature of the sea at the 
end of the northern summer, which, by diminishing the 
sexuality of the oospheres, causes the plant to become an 
asexual form by degeneracy, although morphologically 
retaining the distinction of sex. 
