i88 
Notes . 
the Fucaceae. Hybrids were successfully obtained between Fucus 
vesiculosus ? and F. serratus but all the other experiments 
resulted in failure. The following additional observations may be of 
interest : — 
1. Last November attempts were made by the writer to obtain 
hybrids between Ascophyllum and F. vesiculosus . When antherozoids 
of the latter were added to eggs of the former, no evidence of fertiliza- 
tion was observed : but the reverse cross ( Ascophyllum and F. vesi- 
culosus $ ) gave a limited number- — about one in twenty — of segmenting 
oospores, while a much larger number became invested with walls. 
Similar results were given on two other occasions on which the 
experiment was tried. One of these lots, started Nov. io, 1898, was 
allowed to grow, and at the date of writing (Feb. n, 1899) the plants 
are quite healthy; they have long rhizoids, most of them are 
beginning to branch, and several have their first barren conceptacle 
forming. 
2. Antherozoids of F. serratus were added to eggs of Ascophyllum. 
About a fourth of the number produced investing walls, a very few 
showed commencing rhizoids, but only two or three segmented, and 
even these soon stopped growing. 
In view of the recent observations on the fertilization of Halidrys , 
the formation of an investing wall can safely be regarded as evidence 
of the entry of an antherozoid into the egg. It will be interesting to 
see whether the absence of segmentation in such an egg is due to the 
failure of the antherozoid to reach and fuse with the egg-nucleus. 
3. Antherozoids of Halidrys were added to eggs of F. vesiculosus . 
They gyrated on the surface of the eggs exactly as they do on their 
own, but in smaller numbers and for shorter periods. Here no 
evidence of fertilization could be seen. 
4. The circumstance which led to this series of experiments was 
the finding in the Menai Straits of a plant which in external characters 
seemed intermediate between an Ascophyllum and a Fucus , while the 
conceptacles were found to contain both antheridia and oogonia. 
J. LLOYD WILLIAMS, Bangor. 
