54 SEAWEEDS 
ment of the other. They contain paraphyses only, 
which are generally of great length and protrude 
through the ostiole. Observations are desirable on 
the paraphyses of both fertile conceptacles and 
cryptostomata, since it is probable that minute 
parasitic Algze have sometimes been mistaken for 
them. There is, moreover, a difference according to 
descriptions in their mode of growth ¢.g.; it appears 
to be acropetal in the cryptostomata of Cystoseira 
and basipetal in those of Turbinaria. Since similar 
cryptostomata of varying shapes, dimensions, and 
modes of origin occur in the Laminariacee (e.g. 
Saccorhiza, Adenocystis) and in other Pheophycec, such 
as Chnoospora, Hydroclathrus, and Scytothamnus, any 
discussion of their nature must involve the con- 
sideration of these forms as well as the conceptacles 
of peculiar origin in Splachnidiacee bearing non- 
sexual sporangia. 
Thuret has made some interesting experiments on 
hybridity among Fucacew and other Alga—such 
experiments being much facilitated by the fact that 
impregnation takes place outside the plant. Experi- 
ments with different genera (Mucus, Himanthalia, 
Ascophyllum) were unsuccessful, but he obtained 
a hybrid between Mucus vesiculosus 9 and Fucus 
serratus 8, although Fucus vesiculosus could not 
fertilise Fucus serratus 9. That natural hybrids 
occur between these species seems highly probable 
to those who have examined large series of specimens 
and have observed especially the variation of F. 
vesiculosus. It must not be forgotten, however, that 
circumstances of environment, such as growth in 
